Enantioselective Total Synthesis of (-)-Acetylaranotin, a Dihydrooxepine Epidithiodiketopiperazine Julian A. Codelli, Angela L. A. Puchlopek, and Sarah E. Reisman* JACS. ASAP. ct. 24, 2011 DI: 10.1021/ja209354e t-bu 2 C 2 Et 18 steps Ac S S Ac commercially available starting materials acetylaranotin Christopher Rosenker Wipf Group - Current Literature ovember 12, 2011 Chris Rosenker @ Wipf Group Page 1 of 16 12/29/2011
Epidithiodiketopiperazine natural products Epidithiokiketopiperazines (ETP) are a broad collection of fungal metabolites that contain at least 14 different core structures. Biosynthetically arise by the joining of two amino acids which are further functionalized via oxidative pathways Subset contains a 7-membered dihydrooxepine ring Biological activity of dihydrooxepine containing ETPs include inhibition of viral RA polymerase and antiproliferative/apoptotic activity against human cancer cells. S S (!)-emethallicin A Ac S S Ac (!)-acetylaranotin Me Me S S (+)-MPC1001B S S (!)-gliotoxin Gardiner, D. M.; Waring, P.; owlett, B. J. Microbiology 2005, 151, 1021. Codelli, J. A.; Puchlopek, A. L. A.; Reisman, S. E. J. Am. Chem. Soc. 2011, DI: 10.1021/ja209354e. Chris Rosenker @ Wipf Group Page 2 of 16 12/29/2011
Biosynthetic proposal of gliotoxin and aranotin type natural products The biosynthesis of gliotoxin and aranotin type natural products is hypothesized to occur via an epoxidized benzene ring. [] ring expansion gliotoxin type [] aranotin type euss,.; Boeck, L. D.; Brannon, D. R.; Cline, J. C.; DeLong, D. C.; Gorman, M.; uckstep, L. L.; Lively, D..; Mabe, J.; Marsh, M. M.; Molloy, B. B.; agarajan, R.; elson, J. D.; Stark, W. M. Antimicrob. Agents Chemother. 1968, 213. Gardiner, D. M.; Waring, P.; owlett, B. J. Microbiology 2005, 151, 1021. Chris Rosenker @ Wipf Group Page 3 of 16 12/29/2011
Synthetic Methodologies to from xepines Cadogan, Gosney & Co-workers: Cope rearrangement using a highly strained epoxycyclobutane. C 3 S 2 (39%) S 2 10-3 mmg 580 C (55%) White & Co-workers: Cope rearrangement of cis-divinyl epoxide. LiMDS; Ac 2-70 C (70%) Ac CCl 4, 135 C 12 h (94%) Ac TMS TMS TMS Aitken, R. A.; Cadogan, J. I. G.; Gosney, I.; amill, B. J.; McLaughlin, L. M. J. Chem. Soc.; Chem. Comm. 1982, 1164. Clark, D. L.; Chou, W.-.; White, J. B. J. rg. Chem. 1990, 55, 3975. Chris Rosenker @ Wipf Group Page 4 of 16 12/29/2011
Synthetic Methodologies to from xepines Snapper & Leyhane: Thermal fragmentation of highly strained epoxides provides functionalized oxepines. C 2 Me m-cpba C 2 Cl 2 (93%) C 2 Me 200 C, 2 h BT, [0.01 M] C 2 Me 35% 36% C 2 Me a C2 Me C2 Me C 2 Me b C 2 Me C 2 Me Leyhane, A. J.; Snapper, M. L. rg. Lett. 2006, 8, 5183. Chris Rosenker @ Wipf Group Page 5 of 16 12/29/2011
Synthetic Methodologies to from xepines Vargas & Co-workers: Isolated oxepine during structural elucidation of sesquiterpene hydroperoxide. Ac 2, pyridine (31%) Ac Ac Ac Pyr: Kishi & Goodman: Criegee rearrangement of allylic hydroperoxides to form an Aranotin type precursor. 1. (p- 2 Bz) 2, DMAP (5 mol%), -45 to -20 C p- 2 Bz 0.45 torr TBDPS BzBr 2. BF 3 Et 2 (47 mol%) -40 to -20 C, 6 h (45% over two steps) TBDPS BzBr 150 to 250 C (70%) TBDPS BzBr p- 2 TBDPS BzBr Lu, T.; Vargas, D.; Fischer,.. ytochemistry 1993, 34, 737. Goodman, R.; Kishi, Y. J. Am. Chem. Soc. 1998, 120, 9392. Goodman, R. M..D. Thesis, arvard University, May 1998. Chris Rosenker @ Wipf Group Page 6 of 16 12/29/2011
Synthetic Methodologies to from xepines Fustero & Co-workers: Tandem RCM-olefin isomerization methodology. Grubbs II Grubbs II toluene, reflux (60%) toluene, reflux 23% 46% Bräse & Co-workers: Enol-ether RCM on an unprotected allylic alcohol. [Ir(cod)Cl] 2 (10 mol%) ac 3, vinyl acetate Grubbs II, Grubbs-oveyda, Schrock catalysts TBS Boc C 2 t-bu toluene, 100 C (95%, E:Z;8:2) TBS Boc C 2 t-bu TBS Boc C 2 t-bu 1. TBAF, TF (87%) 2. Grubbs II (20 mol%) toluene, 110 C (quant.) Boc C 2 t-bu Fustero, S.; Sáchez-Roselló, M.; Jiménez, D.; Sanz-Cervera, J. F.; del Pozo, C.; Aceña, J. L. J. rg. Chem. 2006, 71, 2706. Gross, U.; ieger, M.; Bräse, S. Chem.-Eur. J. 2010, 16, 11624. Chris Rosenker @ Wipf Group Page 7 of 16 12/29/2011
Synthetic Methodologies to from xepines Clive & Peng: Acid-induced cyclicization of pendant alcohol onto a vinylogous amide. Se MEM S SiMe 3 (Me) 2 C(Me 2 ) TF (70% brsm) Se MEM Me 2 S SiMe 3 TFA, toluene 50 C (77%) Se MEM S SiMe 3 ai 4, TF- 2 (39%) MEM S SiMe 3 Me Me S S (+)-MPC1001B Peng, J.; Clive, D. L. J. rg. Lett. 2007, 9, 2939. Peng, J.; Clive, D. L. J. J. rg. Chem. 2009, 74, 513. Chris Rosenker @ Wipf Group Page 8 of 16 12/29/2011
Synthetic Methodologies to from xepines McDonald & Co-workers W-cat cycloisomerization 1. cat. W(C) 6, Et 3 TF, h!, 55 C 2. Ac 2, DMAP Ac Me W(C) 5 1. Et 3, TF, 60 C 2. Ac 2, Et 3, DMAP Ac 61-82% 82% Jia & Co-workers Ru-cat cylcoisomerization Esteruelas, Saá & Co-workers s-cat cylcoisomerization P 2 Ru R 1 [Cps(py) 3 ]PF 6 R 2 R 4 pyridine, 90 C R 3 R 1 R 2 R 3 R 4 56-68% TF, 80 C 91% Alcázar, E.; Pletcher, J. M.; McDonald, F. E. rg. Lett. 2004, 6, 3877. Koo, B.; McDonald, F. E. rg. Lett. 2007, 9, 1737. Liu, P..; Su, F..; Wen, T. B.; Sung,.. Y.; Williams, I. D.; Jia, G. Chem.-Eur. J. 2010, 16, 7889. Varela-Fernández, A.; García-Yebra, C.; Varela, J. A.; Esteruelas, M. A.; Saá, C. Angew. Chem. Int., Ed. 2010, 49, 4278. Chris Rosenker @ Wipf Group Page 9 of 16 12/29/2011
Reisman Group Retrosynthetic Analysis metal-catalyzed cycloisomerization Ac S S Ac C 2 Et TBS (!)-acetylaranotin t-bu catalytic asymmetric (1,3)-dipolar cycloaddition t-bu 2 C 2 Et C 2 Et TBS C 2 Et commercially available starting materials (-)-acetylaranotin was isolated over 40 years ago and had not yet been synthesized Codelli, J. A.; Puchlopek, A. L. A.; Reisman, S. E. J. Am. Chem. Soc. 2011, DI: 10.1021/ja209354e. Chris Rosenker @ Wipf Group Page 10 of 16 12/29/2011
Catalytic asymmetric (1,3)-dipolar cycloaddition t-bu 2 C C 2 Et 1. CuI (10 mol %) brucin-l (10 mol %) DBU (10 mol %) (50%, 96% ee) 2 C 2. TFA, Et 3 Si, C 2 Cl 2 (77%) >98% ee C 2 Et TFA (!)-brucine $3.34/g (Aldrich) Me Me s 4, M acetone, t-bu 2 95% brucin-l Me Me Cu t-bu Me Me Et Codelli, J. A.; Puchlopek, A. L. A.; Reisman, S. E. J. Am. Chem. Soc. 2011, DI: 10.1021/ja209354e. Kim,. Y.; Shih,.-J.; Knabe, W. E.; h, K. Angew. Chem., Int. Ed.. 2009, 48, 7420. Chris Rosenker @ Wipf Group Page 11 of 16 12/29/2011
Synthesis of Acetylaranotin 2 C C 2 Et TFA 1. -Su, Et 3 2 /dioxane (83%) 2. 3, C 2 Cl 2,!78 C; then DMS (93%) C 2 Et MgBr TF,!78 to 0 C; C 2 Et : TMS then P 3, DIAD C 2 Cl 2, 0 C (76%) C 2 Et ab 4, Et (86%) C 2 Et 1. TBSTf, 2,6-lutidine C 2 Cl 2, 0 C (85%) 2. Ac, TF, 2 (3:1:1) (79%) DMP, pyr, C 2 Cl 2 (93%) TBS C 2 Et TBS C 2 Et Codelli, J. A.; Puchlopek, A. L. A.; Reisman, S. E. J. Am. Chem. Soc. 2011, DI: 10.1021/ja209354e. Chris Rosenker @ Wipf Group Page 12 of 16 12/29/2011
Synthesis of Acetylaranotin: dihydrooxepine formation TBS C 2 Et Conditions C 2 Et TBS Conditions [Rh(cod)Cl] 2, [Rh(cod)(MeC) 2 ]BF 4, CpRuCl[(4-FC 6 4 ) 3 P] 2 (C) 5 W=C(Me)Me, AuCl, Pd(Ac) 2, CuI, AgTf w/ and w/o ligands and additives CS, C 2 Cl 2 pyrrolidine TFA; Cl [Rh(cod)Cl] 2 (5 mol %) (4-FC 6 4 ) 3 P (60 mol %) Cl ab 4, Et (93%) TBS C 2 Et DMF, 85 C (88%) C 2 Et TBS A A LiCl, Li 2 C 3, DMF 100 C (53%) desilylation C 2 Et TBS TBS mixture of mono- & bis-desilylated products C 2 Et 1. TBAF, TF, 0 C (84%) 2. LiCl, Li 2 C 3, DMF 100 C (65%) Codelli, J. A.; Puchlopek, A. L. A.; Reisman, S. E. J. Am. Chem. Soc. 2011, DI: 10.1021/ja209354e. Chris Rosenker @ Wipf Group Page 13 of 16 12/29/2011
Synthesis of Acetylaranotin TBS A C 2 Et Li, Me TBS C 2 Dimerization TBS TBS C 2 Et TBS Me 3 Sn, DCE, 80 C (90%) C 2 TBS A, BP-Cl Et 3, DMF (87%) TBS C 2 Et TBS P Cl BP-Cl Codelli, J. A.; Puchlopek, A. L. A.; Reisman, S. E. J. Am. Chem. Soc. 2011, DI: 10.1021/ja209354e. Chris Rosenker @ Wipf Group Page 14 of 16 12/29/2011
Synthesis of Acetylaranotin TBS C 2 Et TBS TBAF (t-bu) 4 MeC, 70 C 2 atm (76%) amds, TF; S 8, amds; then amds (40%) TBAF (t-bu) 4 MeC, 70 C air (50%) S 4 1. AcCl, DMAP C 2 Cl 2 (70%) 2. S S (100 equiv) Et 3, MeC; then 2 (45%) Ac S S Ac (-)-acetylaranotin (18 steps, 0.45%, from ethylglycinate) Codelli, J. A.; Puchlopek, A. L. A.; Reisman, S. E. J. Am. Chem. Soc. 2011, DI: 10.1021/ja209354e. Chris Rosenker @ Wipf Group Page 15 of 16 12/29/2011
Conclusion Completed the first total synthesis of (-)-acetylaranotin in 18 steps (~0.45 % yield) Synthetic highlights include: Rhodium-catalyzed cycloisomerization/chloride elimination to provide dihydrooxepine Azomethine ylide (1,3)-dipolar cycloaddition gave stereoselective access to functionalized pyrrolidine Complete retention of steroechemistry during epitetrathiodiketopiperazine formation Chris Rosenker @ Wipf Group Page 16 of 16 12/29/2011