Synthesis and Biological Evaluation of Novel 2-Substituted ­Analogues of (-)-Pentenomycin i

475 © 2020. Thieme. All igh s ese ed. Synle 2020, 31, 475–481 Geo g Thieme Ve lag KG, Rüdige s aße 14, 70469 S u ga , Ge many S. A. Zisopoulou e al. Le e Syn le Syn hesis and Biological E alua ion o No el 2-Subs i u ed Analogues o (–)-Pen enomycin I S a oula A. Zisopouloua Spy idon Bousisb,c,d Jö g Haupen halb Jenni e He manne Rol Mülle d,e Anna K. H. Hi sch*b,c,d Dimi i Komio is John K. Gallosa Ch is os I. S a hakis*a 0000-0003-4755-6244 aDepa men o Chemis y, A is o le Uni e si y o Thessaloniki, Uni e si y Campus, 541 24, Thessaloniki, G eece [email p o ec ed] bDepa men o D ug Design and Op imiza ion, Helmhol z Ins i u e o Pha maceu ical Resea ch (HIPS) – Helmhol z Cen e o In ec ion Resea ch (HZI), 66123, Saa b ücken, Ge many [email p o ec ed] cS a ingh Ins i u e o Chemis y, Uni e si y o G oningen, Nijenbo gh 7, 9747 AG G oningen, The Ne he lands dDepa men o Pha macy, Saa land Uni e si y, Campus Building E8.1, 66123 Saa b ucken, Ge many eDepa men o Mic obial Na u al P oduc s, Helmhol z Ins i u e o Pha maceu ical Resea ch (HIPS) – Helmhol z Cen e o In ec ion Resea ch (HZI), Campus Building E8.1, Saa b ücken, Ge many Depa men o Biochemis y and Bio echnology, Uni e si y o Thessaly, Biopolis, 41500, La issa, G eece Published as pa o he Special Sec ion 11 h EuCheMS O ganic Di ision Young In es iga o Wo kshop O O O T O Pd-ca alyzed coupling eac ion HO HO O HO R HO HO O HO X R = n-C8H17 S. au eus s . Newman MIC = 27 µg/mL S. pneumoniae DSM20566 MIC = 9 µg/mL S. pneumoniae DSM11865 MIC = 9 µg/mL and dep o ec ion 17 new pen enomycin de i a i es combined yield ange o coupling and dep o ec ion s eps: 39–94% X = bo h EWGs and EDGs R = a yl, alkyl I Recei ed: 31.10.2019 Accep ed a e e ision: 27.11.2019 Published online: 02.01.2020 DOI: 10.1055/s-0039-1690772; A ID: s -2019-b0592-l Abs ac A lib a y o no el 2-subs i u ed de i a i es o he an ibio ic na u al p oduc pen enomycin I is p esen ed. The new collec ion o an- alogues is di ided in wo main classes, 2-alkynyl- and 2-a yl- de i a i es, which a e accessed by he app op ia e ype o palladium-ca alyzed c oss-coupling eac ion o he 2-iodo-p o ec ed pen enomycin I wi h sui able nucleophiles. The new de i a i es we e es ed o hei ac i i y agains ce ain ypes o bac e ia and one o hem, compound 8h, was ound o exhibi signi ican inhibi o y ac i i y agains se e al G am-pos- i i e bac e ia bu also displayed cy o oxic ac i i y agains euka yo ic cell lines. Key wo ds (–)-pen enomycin, Sonogashi a, Suzuki, an imic obial agen s, G am-posi i e bac e ia (–)-Pen enomycin I (1a) was i s isola ed om he cul- u e b o h o S ep omyces eu y he mus MCRL 0738, by Umino and co-wo ke s in 1973 (Figu e 1).1 The said com- pound is a p incipal membe o a b oade amily o cyclo- pen enoid an ibio ics, which possess mode a e ac i i y agains G am-posi i e and G am-nega i e bac e ia.1a,2 O e he pas ew yea s, we3 and o he s4 ha e demons a ed he po en ial o 2-halogena ed pen enomycin as sui able p e- cu so o de i a iza ion, hus leading o new cyclopen- enones wi h po en ially imp o ed biological p o ile. He ein, we epo a sys ema ic e o o syn hesize a se- ies o analogues o he na u al an ibio ic, co e ing a b oad ange o s e eochemical demand and in oducing a a ie y o unc ional g oups. In he con ex o ou esea ch on he de elopmen o new me hodologies o access chi al cyclo- pen enones om suga -de i ed syn hons, we ha e de- sc ibed he syn hesis o (–)-pen enomycin I h ough an oxi- Figu e 1 Rep esen a i es o he pen enomycin amily Pen enomycins I–III O OH OR2 OR1 O OH OR2 OR1 O OH O OH O OH OH OH 4 5 1a: R1 = H, R2 = H 1b: R1 = H, R2 = OAc 1c: R1 = OAc, R2 = H G-2201-C Dehyd open enomycin I 4 4-Epipen enomycins I–III 2a: R1 = H, R2 = H 2b: R1 = H, R2 = OAc 2c: R1 = OAc, R2 = H 5-Epipen enomycin Echinospo in 3 SYNLETT 0936-52141437-2096 © Geo g Thieme Ve lag S u ga · New Yo k 2020, 31, 475–481 le e de Dieses Dokumen wu de zum pe sönlichen Geb auch he un e geladen. Ve iel äl igung nu mi Zus immung des Ve lages. 476 © 2020. Thieme. All igh s ese ed. Synle 2020, 31, 475–481 S. A. Zisopoulou e al. Le e Syn le da i e elimina ion p ocess on sui able ammonium sal s (Scheme 1, sequence 5 → 6 → 1a).5 Unexpec edly, we ob- se ed ha when iodide was used as he coun e ion in he ammonium sal 5, he espec i e 2-iodo-p o ec ed pen- enomycin 7 was a o ded. This ‘undesi able’ side p oduc pe ec ly se ed he pu poses o ou syn he ic plan o p e- pa e a lib a y o de i a i es o he na u al an ibio ic in o - de o imp o e i s mode a e biological ac i i y. In doing so, palladium-ca alyzed c oss-coupling eac ions we e hough o be he mos sui able means, a ac suppo ed by he wo k o Negishi and Johnson on ela ed c oss-coupling eac ions o 2-iodo-cycloalkenones.4 Scheme 1 P ecu so and gene al scheme o de i a iza ion The i s class o de i a i es we en isaged was he 2- alkynyl-subs i u ed pen enomycins accessible ia he well- es ablished Sonogashi a eac ion.6 Indeed, unde ypical e- ac ion condi ions,7 he coupling o 2-iodopen enomycin 7 wi h a ious e minal alkynes 9a–i (see gene al eac ion scheme in Table 1), in he p esence o CuI and ca aly ic amoun s o [Pd(PPh3)2Cl2], deli e ed he desi ed p oduc s in good o excellen yield. A e emo al o bo h p o ec ing g oups, in one ope a ion, unde s ongly acidic condi ions he inal 2-alkynyl-pen enomycins 8a–i we e ob ained. Table 1 Coupling Reac ions o 2-Iodopen enomycin 7 wi h Alkynes 9a–ia and Subsequen Dep o ec ion o Pen enomycin De i a i es 8a–ib D . Ch is os S a hakis was bo n in Spa a, G eece and s udied chem- is y a A is o le Uni e si y o Thessaloniki. A he same uni e si y he e- cei ed his doc o al diploma in o ganic chemis y in 2007, unde he guidance o P o . Gallos. In 2008 he joined he esea ch g oup o P o . Snyde a Columbia Uni e si y in he ci y o New Yo k, whe e he ex- plo ed he exci ing chemis y o polyphenol na u al p oduc s. A he end o 2009 he e u ned o A hens, G eece o join an ongoing esea ch p og am on new aminoglycoside an ibio ics supe ised by D . Vou - loumis a he Na ional Cen e o Na u al Sciences. D . S a hakis com- ple ed his pos doc o al s udies in he esea ch eam o P o . Paul Knochel a Ludwig Maximillian Uni e si y in Munich (2011–2012), whe e he gained aluable expe ience in o ganome allic chemis y. Fo he nex i e yea s (2013–2018) D S a hakis wo ked as senio e- sea ch scien is a Pha ma hen Pha maceu icals, whe e he was in ol ed in he de elopmen o no el scalable ou es o he syn hesis o se e al ac i e pha maceu ical ing edien s (APIs). Since July 2018, he is an assis- an p o esso a he Chemis y Depa men o A is o le Uni e si y o Thessaloniki. The main esea ch e o s o his g oup ocus on he o al syn hesis o cons uc i ely challenging molecules and he de elopmen o no el me hodologies ha p omo e s uc u al complexi y. L-a abinose OO HO NMe3 T O I [O] OO O T O I s eps i) coun e ion exchange ii) oxida ion OO O T O 7 5 6 1a Pd-ca alyze d coupling eac ion HO OH O HO pen enomycin analogues 8 R En y Alkyne 9Yield o 10 (%) Yield o 8 (%) 1 9a 10a 90 8a 82 2 9b 10b 89 8b 87 OO O T O I OO O T O 7 10a–i HO OH O HO R 8a–i R 90% aq. TFA 9a–i, [Pd(PPh3)2Cl2] 72–90% 54–96% CuI, iP 2NH THF, 25 °C O O O T O Ph O HO HO HO Ph O O O T O Tol O HO H O HO Tol Dieses Dokumen wu de zum pe sönlichen Geb auch he un e geladen. Ve iel äl igung nu mi Zus immung des Ve lages. 477 Thieme. All igh s ese ed. Synle 2020, 31, 475–481 S. A. Zisopoulou e al. Le e Table 1 (con inued) Syn le In he ligh o he abula ed esul s, i is easily deduced ha ou iodo-cyclopen enone p ecu so 7 ope a ed as a pe ec coupling pa ne , leading o he an icipa ed p od- uc s 10 in excellen yields (72–90%) unde he desc ibed e- ac ion condi ions. A a ie y o subs i u ed a yl alkynes (Ta- ble 1, en ies 1–6) was inco po a ed as he alkyne compo- 3 9c 10c 76 8c 81 4 9d 10d 79 8d 89 5 9e 10e 75 8e 93 6 9 10 75 8 95 7 9g 10g 72 8g 54 8 9h 10h 85 8h 96 9 9i 10i 82 8i 90 a To 7 (0.18 mmol) in THF (3.5 mL) we e added successi ely he co esponding alkyne (0.36 mmol), CuI (10 mg, 0.05 mmol), iP 2NH (0.13 mL, 0.91 mmol), and [Pd(PPh3)2Cl2] (8 mg, 0.01 mmol). The eac ion p oceeded a 25 °C o 1–2 h. b 90% aqueous TFA a 0–25 °C. En y Alkyne 9Yield o 10 (%) Yield o 8 (%) O O O T O O HO HO HO B O O O T O B O HO HO HO B Cl O O O T O Cl O HO HO HO Cl Cl O O O T O Cl O HO HO HO Cl OH O O O T O OH 3 O HO HO HO OH 3 6 O O O T O 6 O HO HO HO 6 3 O O O T O 3 O HO HO HO 3 Dieses Dokumen wu de zum pe sönlichen Geb auch he un e geladen. Ve iel äl igung nu mi Zus immung des Ve lages. 478 Thieme. All igh s ese ed. Synle 2020, 31, 475–481 S. A. Zisopoulou e al. Le e Table 2 (con inued) Syn le nen bea ing a ange o unc ional g oups o a ious s e eochemical and elec onical p o iles. In e e y case, he desi ed coupling p oduc was e icien ly deli e ed and iso- la ed by column ch oma og aphy. In he same ein, alkyl- subs i u ed e minal alkynes we e coupled e ec i ely wi h p o ec ed iodo-pen enomycin 7 in yields anging om 72– 85%, unde he same eac ion condi ions (Table 1, en ies 7–9). Na u al p oduc analogues 8a–i we e ob ained a e acidic ea men in 90% aqueous TFA, ensu ing emo al o bo h he iphenylme hyl e he and he ace al p o ec ing g oups. Due o he enhanced lipophilic cha ac e o he p o- duced de i a i es, a simple pu i ica ion by column ch oma- og aphy was enough o p o ide a ma e ial o app op ia e pu i y (>95%) o biological es ing. Nex , we p oceeded wi h he 2-a yl-sus i u ed pen eno- mycin de i a i es 13a–h ha we in ended o access ia a Suzuki eac ion be ween 7 and he co esponding a ylbo- onic acids 11a–h (see gene al eac ion scheme in Table 2),8 ollowed by global dep o ec ion. Table 2 Coupling Reac ions o 2-Iodopen enomycin 7 wi h A ylbo on- ic Acids 11a–ha and Subsequen Dep o ec ion o Pen enomycin De i a- i es 13a–hb En y Bo onic acid 11 Yield o 12 (%) Yield o 13 (%) 1 11a 12a 92 13a 99 2 11b 12b 82 13b 90 3 11c 12c 85 13c 90 4 11d 12d 99 13d 67 OO O T O I OO O T O 7 12a–h HO OH O HO R 13a–h R 90% aq. TFA 11a–h, [Pd(Ph3P)2Cl2] Ag2O, Ph3As THF/H2O, 25 °C 82–99% 59–99% B HO OH O O O T O O HO HO HO B nBu HO OH O O O T O nBu O HO HO HO nBu B NO2 HO OH O O O T O O2N O HO HO HO O2N BOHHO O O O T O O HO HO HO A e sc eening se e al ca aly ic sys ems, we ound ha he combina ion o [Pd(PPh3)2Cl2] and Ph3As as he ligand was he op imum one o a clean con e sion in o he cou- pling p oduc .9 In he p esence o he said ca alys and Ag2O, as he base, in a sol en sys em THF/H2O (3:1), he coupling o 2-iodo-enone 7 wi h a ious a yl bo onic acids 11a–h was success ully accomplished. The eac ion wi h mode a ely o elec on- ich nucleophiles (Table 2, en ies 1, 2, and 4–8) was ealized in excellen yields (82–99%). E en a he deac i a ed bo onic acids eac ed smoo hly unde he desc ibed eac ion condi ions (Table 2, en y 3). In con- as , elec on-de icien bo onic acids such as 2,6-di luo o- phenyl bo onic acid (11i) and 3-py idylbo onic acid (11j) ga e no eac ion wi h any o he sc eened ca aly ic sys ems. Global dep o ec ion o he coupling p oduc s 12a–h a o d- ed, a e ypical pu i ica ion, he unp o ec ed 2-a yl-pen- enomycins 13a–h in 59–99% yield. 5 11e 12e 94 13e 99 6 11 12 86 13 98 7 11g 12g 89 13g 99 8 11h 12h 98 13h 59 9 11i 11j NRc a To 7 (0.18 mmol) in THF (2.25 mL) and H2O (0.75 mL) we e added succes- si ely he co esponding bo onic acid (0.27 mmol), Ag2O (67 mg, 0.29 mmol), Ph3As (12 mg, 0.04 mmol), and [Pd(PPh3)2Cl2] (7 mg, 0.018 mmol). The eac ion p oceeded a 25 °C o 1–2 h. b 90% aqueous TFA 0 o 25 °C. c NR: no eac ion. En y Bo onic acid 11 Yield o 12 (%) Yield o 13 (%) B HO OH O O O T O O HO HO HO B HO OH O O O T O O HO HO HO B HO OH Ph O O O T O Ph O HO HO HO Ph B HO OH OO O O T O O O HO HO HO O B HO OH F F BNHO OH Dieses Dokumen wu de zum pe sönlichen Geb auch he un e geladen. Ve iel äl igung nu mi Zus immung des Ve lages. 479 © 2020. Thieme. All igh s ese ed. Synle 2020, 31, 475–481 S. A. Zisopoulou e al. Le e Syn le The an imic obial ac i i y o he new compounds was es ed agains h ee ep esen a i e s ains, one G am-posi- i e and wo G am-nega i es, namely S aphylococcus au- eus s ain Newman, Esche ichia coli K12, and Pseudomonas ae uginosa PA14 (Table 3). Due o solubili y limi s, he com- pounds we e es ed a he maximum soluble concen a ion. The designed de i a i es 8a–i and 13a–h we e ound no o exhibi any an imic obial e ec agains E. coli and P. ae ugi- nosa, indica ing ha G am-nega i e s ains a e no sensi- i e o he ac ion o he a o emen ioned compounds. In con as , de i a i es 8a, 8d, 8 , and 8h exhibi ed mode a e o good inhibi ion o he g ow h o S. au eus, which was su- pe io o he one exe ed by he na u al p oduc 1a (Table 3). The obse ed di e ence in ac i i y among he wo class- es o bac e ia may be a ibu ed o he di e ence in hei ype o cell wall and he abili y o he compounds o pene- a e hem, as well as he educ ion o he in acellula con- cen a ion o he compounds by e lux pumps. Table 3 Minimum Inhibi o y Concen a ion (MIC) Values o Compounds 8a–i and 13a–h agains S. au eus, E. coli, and P. ae uginosa (in Μ) Based on a ecen li e a u e epo ,10 he an imic obial ac i i y o 2-phenyl-pen enomycin (analogue 13a, Table 2) agains se e al s ains, including S. au eus, En e ococcus ae- cium, and P. ae uginosa, was a enua ed compa ed o he o iginal na u al p oduc . By analogy, we obse ed ha when an a oma ic g oup was in oduced a he -posi ion (compounds 13a–h), he an imic obial ac i i y was com- ple ely abolished (Table 3). Howe e , he ac i i y was e- s o ed when an in e media e linke o a long chain was in- co po a ed, such as in 8a, 8d, 8 , and 8h. Mo e speci ically, compound 8h, which bea s a long alipha ic chain o en ca - bon a oms, p o ed o be he mos po en an imic obial agen . The ce ain leng h and he lexibili y o his chain is suspec ed o be he eason o i s ac i i y, while 8i, a de i a- i e wi h a sho e chain by h ee ca bon a oms, is inac i e. Finally, de i a i es 8d and 8 , which ha e an a oma ic ing connec ed o he iple bond and bea a halogen a me a o pa a posi ion, a e ac i e bu less po en . In o de o es he ac i i y o he designed analogues agains addi ional G am-posi i e s ains, he mos po en inhibi o 8h was sc eened agains he pa hogens indica ed in Table 4. The compound does no show any an imic obial ac i i y agains En e ococcus aecium and En e ococci aeca- lis, as well as agains Mycobac e ium smegma is a concen- a ions below 35 g/mL. No ewo hy, 8h exhibi s a mini- mum inhibi o y concen a ion (MIC) o 9 g/mL agains S ep ococcus pneumoniae, making i one o he mos ac i e de i a i es o pen enomycin I epo ed in he li e a u e so a . In e es ingly, i shows he same MIC alue agains a penicillin- esis an s ain o S. pneumoniae (PRSP), hus ex- cluding possible c oss- esis ance. Table 4 MIC o 8h agains Se e al Pa hogenic G am-Posi i e Bac e ia. Finally, we es ed he iabili y o h ee human cell lines (A549, HEK293, and HepG2) a e ea men wi h com- pound 8h. The compound shows cy o oxic e ec s agains he selec ed cell lines a 25 Μ (Table 5), indica ing ha u - he s uc u al op imiza ion is equi ed o ackle his d aw- back. On he o he hand, a deepe explo a ion o he po en- ial o compound 8h o ac as an an icance agen is wo hy o being unde aken. In summa y, we success ully syn hesized a small lib a y o 2-alkynyl, and 2-a yl-de i a ized pen enomycins based on ypical palladium-ca alyzed coupling eac ions.11 The no el analogues o he na u al an ibio ic we e es ed o hei an imic obial ac i i y agains bo h, G am-posi i e and G am-nega i e bac e ia. 2-A yl-modi ied pen enomycins show no special ac i i y agains bo h ypes o bac e ia, while om he 2-alkynyla ed de i a i es, he one bea ing a Compound S. au eus s . Newman E. coli K12 P. ae uginosa PA14 8a 500 >500 >500 8b >500 >500 >500 8c >250 >250 >250 8d 231 >250 >250 8e >250 >250 >250 8 222 >250 >250 8g >250 >250 >250 8h 98 >250 >250 8i >250 >250 >250 13a >500 >500 >500 13b >500 >500 >500 13c >500 >500 >500 13d >500 >500 >500 13e >500 >500 >500 13 >500 >500 >500 13g >250 >250 >250 13h >500 >500 >500 1a >500 – – Indica o s ains MIC (g/mL) S. pneumoniae DSM-20566 9 S. pneumoniae DSM-11865a 9 E. aecalis DSM-12956 >35 E. aecium DSM-17050b>35 E. aecalis DSM-20478 >35 E. aecalis DSM-2570 >35 E. aecium DSM-20477 >35 M. smegma is mc2155 >35 a PRSP: penicillin- esis an S. pneumoniae. b VRE: ancomycin- esis an En e ococcus aecium. Dieses Dokumen wu de zum pe sönlichen Geb auch he un e geladen. Ve iel äl igung nu mi Zus immung des Ve lages. 480 © 2020. Thieme. All igh s ese ed. Synle 2020, 31, 475–481 S. A. Zisopoulou e al. Le e Syn le long alipha ic chain o en ca bon a oms, 8h, p o ed o be a s ong inhibi o o G am-posi i e S. au eus and S. pneumo- niae s ains. The leng h o he alipha ic chain was demon- s a ed o be c ucial as he co esponding analogue wi h a sho e chain by h ee ca bon a oms, 8i, showed no ac i i y. In addi ion, compound 8h shows cy o oxic e ec agains ce ain cell lines, some o hem being cance cells, indica - ing po en ial an icance ac ion. Funding In o ma ion A.K.H.H. g a e ully acknowledges he Eu opean Resea ch Council (ERC, G an No. 757913), he Helmhol z-Associa ion’s Ini ia i e and Ne wo king Fund, and he Eu opean Union's Ho izon 2020 esea ch and inno a ion p og amme (COFUND-ALERT, G an No. 665250). Eu opean Resea ch Council (757913)Ho izon 2020 (665250) Acknowledgmen Vic o ia Schmi , Dennis Thomas Jene , and Jeanine Jung a e hanked o he echnical suppo . Suppo ing In o ma ion Suppo ing in o ma ion o his a icle is a ailable online a h ps://doi.o g/10.1055/s-0039-1690772. Suppo ing In o ma ionSuppo ing In o ma ion Re e ences and No es (1) (a) Umino, K.; Fu umai, T.; Ma suzawa, N.; Awa aguchi, Y.; I o, Y.; Okuda, T. J. An ibio . 1973, 26, 506. (b) Umino, K.; Takeda, N.; I o, Y.; Okuda, T. Chem. Pha m. Bull. 1974, 22, 1233. (2) Umino, K.; Yamaguchi, T.; I o, Y. Chem. Pha m. Bull. 1974, 22, 2113. (3) Ch is os S a hakis, Disse a ion; A is o le Uni e si y o Thessa- loniki: G eece, 2007. (4) (a) Mille , M. W.; Johnson, C. R. J. O g. Chem. 1997, 62, 1582. (b) Negishi, E. J. O ganome . Chem. 1999, 576, 179. (c) Negishi, E.; Tan, Z.; Liou, S.-Y.; Liao, B. Te ahed on 2000, 56, 10197. (d) Pohmako , M.; Kambu ong, S.; Tuchinda, P.; Kuhaka n, C. Te ahed on 2008, 64, 6315. (5) (a) Gallos, J. K.; Damianou, K. C.; Dellios, C. C. Te ahed on Le . 2001, 42, 5769. (b) Gallos, J. K.; S a hakis, C. I.; Ko oulas, S. S.; Koumbis, A. E. J. O g. Chem. 2005, 70, 6884. (6) (a) Sonogashi a, K.; Tohda, Y.; Hagiha a, N. Te ahed on Le . 1975, 16, 4467. (b) Sonogashi a, K. J. O ganome . Chem. 2002, 653, 46. (7) Typical P ocedu e o he Sonogashi a Coupling 2-Iodopen enomycin (7, 100 mg, 0.181 mmol, 1.0 equi ) was dissol ed in THF (3.5 mL) and Pd(PPh3)2Cl2 (8 mg, 0.011 mmol, 0.06 equi ) and CuI (10 mg, 0.05 mmol, 0.3 equi ) we e added successi ely. The mix u e was deoxygena ed and lashed wi h a gon ca e ully and hen was cooled o 0 °C. 1-Decyne (65.3 L, 0.362 mmol, 2.0 equi ) was added d opwise, ollowed by addi- ion o iP 2NH (0.13 mL, 0.905 mmol, 5 equi ). The eac ion mix u e was s i ed a oom empe a u e o 2 h be o e i was dilu ed wi h E OAc and acidi ied wi h 1 N HCl. The o ganic laye was sepa a ed, and he aqueous laye was ex ac ed wi h E AOc (2 × 10 mL). The combined o ganic laye s we e d ied o e Na2SO4. The sol en was emo ed in acuo, and he esidue was pu i ied by lash column ch oma og aphy (hexanes/E OAc, 15:1) o a o d he enone 10h (87mg) in 85% yield. Nex , compound 10h was dissol ed in a mix u e 90% TFA/H2O (2.0 mL) a 0 °C, and he esul ing solu ion was s i ed o 90 min a his empe a u e. Upon comple ion o dep o ec ion, as de e mined by TLC, ola iles we e emo ed unde educed p es- su e. The esidue was dissol ed in me hanol and e apo a ed ill d y. The abo e p ocedu e was epea ed wice. The esidue was pu i ied by lash column ch oma og aphy using E OAc/MeOH (9:1) as he eluen o a o d 8h as a yellow s icky oil (42 mg, 96% yield). 1H NMR (500 MHz, CD3OD):  = 7.53 (d, J = 3.0 Hz, 1 H), 4.74 (d, J = 3.0 Hz, 1 H), 3.69 (d, J = 10.8 Hz, 1 H), 3.55 (d, J = 10.8 Hz, 1 H), 2.40 ( , J = 7.1 Hz, 2 H), 1.60–1.52 (m, 2 H), 1.43 (dq, J = 13.0, 6.7 Hz, 2 H), 1.34–1.29 (m, 8 H), 0.90 ( , J = 6.7 Hz, 3 H). 13C NMR (125 MHz, CD3OD):  = 204.0, 161.3, 129.7, 98.7, 75.4, 70.4, 70.0, 63.0, 31.6, 28.9, 28.8, 28.5, 28.1, 22.3, 18.7, 13.0. FTIR (nea ): 3462, 2913, 2234, 1738, 1492, 1245, 704 cm–1. []D25 +13.6° (c 1.57 E OH). HRMS (ESI): m/z [M – H]– calcd o C16H23O4: 279.1596; ound: 279.1589. (8) Typical P ocedu e o he Suzuki Reac ion 2-Iodopen enomycin (7, 100 mg, 0.181 mmol, 1.0 equi ) was dissol ed in a mix u e o THF (2.5 mL) and H2O (0.75 mL). Naph- halene-1-bo onic acid (47 mg, 0.272 mmol, 1.5 equi ), Ag2O (67 mg, 0.29 mmol, 1.6 equi ), Ph3As (12 mg, 0.04 mmol, 0.2 equi ), and Pd(PPh3)2Cl2 (7 mg, 0.018 mmol, 0.1 equi ) we e added successi ely, and he eac ion was s i ed a ambien empe a u e o 3 h. Upon comple ion he mix u e was il e ed h ough Celi e. The il a e was concen a ed unde educed p essu e and pu i ied by lash column ch oma og aphy (hex- anes/E OAc, 15:1) o a o d he espec i e enone 12d (100 mg, 99% yield). Nex , compound 12d was dissol ed in a mix u e o 90% TFA/H2O a 0 °C, and he esul ing solu ion was s i ed o 90 min a his empe a u e. When he eac ion was comple ed as de e mined by TLC, ola iles we e emo ed unde educed p essu e, and he esidue was dissol ed in me hanol and e apo a ed down. The abo e p ocedu e was epea ed wice, and he esidue was pu i- ied by lash column ch oma og aphy using E OAc/MeOH (9:1) as he eluen . De i a i e 13d was a o ded as b own solid (32 mg, 67% yield, mp 52–55 °C). 1H NMR (500 MHz, CD3OD):  = 7.89 (d, J = 8.0 Hz, 2 H), 7.82 (d, J = 8.3 Hz, 1 H), 7.69 (d, J = 2.8 Hz, 1 H), 7.49 ( , J = 7.6 Hz, 2 H), 7.46–7.43 (m, 1 H), 7.38 (d, J = 7.1 Hz, 1 H), 4.97 (d, J = 2.8 Hz, 1 H), 3.89 (d, J = 10.5 Hz, 1 H), 3.73 (d, J = 10.5 Hz, 1 H). 13C NMR (125 MHz, CD3OD):  = 205.7, 160.2, 144.7, 133.6, 131.2, 129.3, 128.6, 127.9, 126.5, 125.8, 125.6, 125.1, 124.7, 76.2, 70.3, 63.4. FTIR (nea ): 3388, 2924, 2852, 1715, 1509, 1141, 778 cm–1. []D25 –20.5° (c 1.46 E OH). HRMS (ESI): m/z [M – H]– calcd o C16H13O4: 269.0814; ound: 269.0819. Table 5 Viabili y agains Compound 8h and Re e ence Compounds o Th ee Human Cell Lines Exp essed as (% Viabili y). Viabili y o cells (%) Compound A549 HEK293 HepG2 8h (25 M) 20 ± 3 6 ± 1 28 ± 13 doxo ubicin (1 M) 55 ± 2 58 ± 1 79 ± 1 i ampicin (100 M) 97 ± 1 59 ± 1 83 ± 3 Dieses Dokumen wu de zum pe sönlichen Geb auch he un e geladen. Ve iel äl igung nu mi Zus immung des Ve lages. 481 © 2020. Thieme. All igh s ese ed. Synle 2020, 31, 475–481 S. A. Zisopoulou e al. Le e Syn le (9) (a) Ruel, F. S.; B aun, M. P.; Johnson, W. S. O g. Syn h., Coll. Vol. X 2004, 467. (b) Miyau a, N.; Suzuki, A. Chem. Re . 1995, 95, 2457. (10) Kamishima, T.; Suzuki, M.; Aoyagi, S.; Wa anabe, T.; Koseki, Y.; Kasai, H. Te ahed on Le . 2019, 60, 1375. (11) An ibac e ial Tes ing Compounds we e p epa ed as DMSO s ock solu ions, and minimum inhibi o y concen a ions (MIC) we e de e mined as desc ibed in he li e a u e.12 Bac e ia we e handled acco ding o s anda d p ocedu es and we e ob ained om he Ge man Col- lec ion o Mic oo ganisms and Cell Cul u es (DSMZ) o we e pa o ou in e nal s ain collec ion. In b ie , bac e ial cul u es we e dilu ed in T yp ic Soy B o h (TSB; 1.7% pep one casein, 0.3% pep one soymeal, 0.25% glucose, 0.5% NaCl, 0.25% K2HPO4; pH 7.3; o En e ococci and S ep ococci), Lu ia B o h (LB; 0.05% sodium chlo ide, 1.0% yp one, and 0.5% yeas ex ac o S. au eus, E. coli, and P. ae uginosa), BBL Middleb ook 7H9 wi h glyce ol (0.1% w/ casi one, 5.6 g/mL palmi ic acid, 5 mg/mL bo ine se um albumin, 4 g/mL ca alase; o M. smegma is), o Mülle -Hin on b o h (0.2% bee in usion solids, 1.75% casein hyd olysa e, 0.15% s a ch; pH 7.4; o all o he lis ed bac e ia) o achie e a inal inoculum o app oxima ely 104 o 105 colony- o ming uni s (c u)/mL. Compounds we e es ed in se ial dilu- ion (0.06–128 M) in 96-well pla es, and MIC alues we e de e mined by isual inspec ion a e 16–48 h incuba ion a 37 °C. MTT Assay HepG2 (human hepa ocellula ca cinoma), HEK293 (human emb yonal kidney), and A549 (human lung ca cinoma) cells (2 × 105 cells pe well) we e seeded in 24-well in la -bo omed pla es. Cul u ing o cells, incuba ions and OD measu emen s we e pe o med as desc ibed p e iously wi h small modi ica- ion.13 A e seeding o 24 h, he incuba ion was s a ed by he addi ion o compounds in a inal DMSO concen a ion o 1%. The li ing cell mass was quan i ied a e 48 h. Ri ampicin was used as nega i e con ol, doxo ubicin as posi i e con ol. Full expe imen al de ails o he syn hesis o all pen enomycin de i a i es, as well as pic u es o 1H NMR and 13C NMR spec a he eo a e p o ided in he Suppo ing In o ma ion sec ion. (12) Hü el, S.; Tes olin, G.; He mann, J.; Planke, T.; Gille, F.; Mo eno, M.; S adle , M.; B öns up, M.; Ki schning, A.; Mülle , R. Angew. Chem. In . Ed. 2017, 56, 12760. (13) Haupen hal, J.; Baeh , C.; Zeuzem, S.; Piipe , A. In . J. Cance 2007, 121, 206. Dieses Dokumen wu de zum pe sönlichen Geb auch he un e geladen. Ve iel äl igung nu mi Zus immung des Ve lages.