Calendars

A concise enantioselective synthesis of (+)-goniodiol and (+)-8-methoxygoniodiol via Co-catalyzed HKR of anti-(2SR, 3RS)-3-methoxy-3-phenyl-1, 2-epoxypropane

Description
A concise enantioselective synthesis of (+)-goniodiol and (+)-8-methoxygoniodiol via Co-catalyzed HKR of anti-(2SR, 3RS)-3-methoxy-3-phenyl-1, 2-epoxypropane
Categories
Published
of 3
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Related Documents
Share
Transcript
   A concise enantioselective synthesis of (+)-goniodiol and(+)-8-methoxygoniodiol via Co-catalyzed HKR of   anti -(2  SR  ,3  RS  )-3-methoxy-3-phenyl-1, 2-epoxypropane I. N. Chaithanya Kiran, R. Santhosh Reddy, Gurunath Suryavanshi, Arumugam Sudalai ⇑ Chemical Engineering and Process Development Division, National Chemical Laboratory, Pashan Road, Pune 411 008, India a r t i c l e i n f o  Article history: Received 6 October 2010Revised 15 November 2010Accepted 16 November 2010Available online 19 November 2010 Keywords: StyryllactonesRacemic  anti -epoxideHydrolytic kinetic resolutionAllylationDiastereoselectivity a b s t r a c t A short, enantioselective synthesis of (+)-goniodiol and (+)-8-methoxygoniodiol, cytotoxic styryllactones,has been achieved in high optical purities (99% ee). The strategy employs Co-catalyzed HKR of racemic anti -(2 SR ,3 RS  )-3-methoxy-3-phenyl-1,2-epoxypropane andLewisacid-mediated diastereoselectiveally-lation of aldehyde as chiral inducing key reactions.   2010 Elsevier Ltd. All rights reserved. The genus  Goniothalamus  (Annonaceae) consists of over 115species of shrubs and treelets growing abundantly in the rain for-ests of tropical Asia. 1 The extracts and leaves of   Goniothalamus  spe-cies have traditionally been used as folk medicine: for example, inthe treatment of edema and rheumatism, 2 abortifacient, 3 laborpain, 4 etc. In particular, both (+)-goniodiol ( 1 ) 4 and (+)-8-meth-oxygoniodiol ( 2 ), 5 which belong to styryllactone family, were iso-lated from  Goniothalamus sesquipedalis  and  Goniothalamusamuyon , respectively. These bioactive natural products  1 – 5 (Fig.1) with relatively small and densely functionalised moleculesare found to exhibit significant cytotoxic activity 6 including antitu-mor and antifungal properties as well as antibiotic potential. Thus,their unique structural features coupled with potent biologicalactivities make them ideal targets for testing new synthetic meth-odology. Consequently, there have been important synthetic ef-forts toward styryllactones  1 – 5  resulting in the number of theirtotal synthesis. 7 However, some of the reported methods sufferfrom certain limitations such as use of chiral building blocks andexotic reagents, involvement of longer reaction sequence, etc. Wehave recently reported a flexible, novel method that employs Co-catalyzed HKR (Hydrolytic Kinetic Resolution) of racemic  syn -alk-oxy epoxides to generate the corresponding diols and epoxideswith two-stereocenters of high optical purity (97–98% ee) in a sin-gle step. 8a By applyingthe same strategy, we have achieved, for thefirst time, HKR of racemic  anti -methoxy epoxide  6  (Scheme 1) anddemonstrated its effectiveness in the short enantioselective syn-thesis of (+)-goniodiol ( 1 ) and (+)-8-methoxygoniodiol ( 2 ).Firstly, the starting material  anti -methoxy epoxide  6  was pre-paredin three steps startingfromcommercially availablecinnamylalcohol, which on epoxidation with  m CPBA gave the epoxy alcohol 0040-4039/$ - see front matter    2010 Elsevier Ltd. All rights reserved.doi:10.1016/j.tetlet.2010.11.085 ⇑ Corresponding author. Tel.: +91 20 25902174; fax: +91 20 25902676. E-mail address:  a.sudalai@ncl.res.in (A. Sudalai). OOOHOHOOOHOHOOOHOHOOOROH (-)-6- epi -Goniodiol ( 3 )R = H; (+)-Goniodiol ( 1 )R = Me; (+)-8-Methoxygoniodiol ( 2 ) (-)-8- epi -Goniodiol ( 5 )(+)-7- epi -Goniodiol ( 4 ) Figure 1.  Structures of bioactive styryllactones.Tetrahedron Letters 52 (2011) 438–440 Contents lists available at ScienceDirect Tetrahedron Letters journal homepage: www.elsevier.com/locate/tetlet  9 . The regiospecific opening of epoxide  9  with MeOH was achievedquantitatively to give diol  10 , which was further converted to race-mic  anti -methoxy epoxide  6  in a two-step reaction sequence: (i)selective monotosylation of primary alcohol (TsCl, Bu 2 SnO, Et 3 N,DMAP, CH 2 Cl 2 ); (ii) formation of epoxide under basic conditions(K 2 CO 3 , MeOH)(Scheme 2). Then, webecameinterested in subject-ing  anti -(2 SR , 3 RS  )-3-methoxy-3-phenyl-1, 2-epoxypropane  6  toHKR with ( S  , S  )-salen Co(OAc) complex 8a,b (0.5 mol %) and H 2 O(0.5 equiv), which produced the corresponding chiral diol  7 16 (47%, 98% ee) and epoxide  8  (48%, 96% ee) in high optical purity(Scheme 1). As compared to the reported methods, the presentstrategy employs a truly catalytic amount of chiral cobalt-basedsalencomplexandwater astheonlyreagentundermildconditionsthat afforded diol  7  and epoxide  8 , which are useful intermediatesin the asymmetric synthesis of other members of styryllactonefamily. The chiral diol  7  was readily separated from epoxide  8  bythe column chromatographic purification and its primary hydroxylfunction selectively protected (TBSCl, imid., CH 2 Cl 2 , 25   C) 9 to ob-tain the corresponding silyl ether  11  in 90% yield (Scheme 3). Pro-tectionof secondaryalcohol in  11 as benzylether (BnBr,NaH, DMF,25   C) 10 was then carried out to produce the protected ether  12  in95% yield. The selective deprotection of TBS group was achieved(TBAF, THF, 25   C) to give back the primary alcohol  13  in 91% yield.The smooth IBX oxidation of alcohol  13  at 25   C gave the corre-sponding crude aldehyde, which was found to be quite unstableon exposure both to moisture as well as air. Hence, this crude alde-hyde, was immediately subjected to Ti-mediated diastereoselec-tive allylation (TiCl 4 , tri - n - butyl allyl stannane, CH 2 Cl 2 ,   78   C) tofurnish the key intermediate homoallylic alcohol  14  in 73% yieldover two-steps as a single diastereomer as determined from its 1 H NMR spectrum of the crude product. 11 Esterification of alcohol 14  with ( E  )-cinnamoyl chloride (py, DMAP, CH 2 Cl 2 , 25   C) gave thecorresponding ester  15  in 64% yield. 12 Ring closing metathesis of the cinnamate ester  15  with Grubbs’ second generation catalystled to the isolation of   a -pyrone  16  in 76% yield. 12 Finally, the oxi-dative deprotection of benzyl group in  16  with DDQ was carried OMeOOHOMeOH+OMeO anti -6 (2 SR , 3  RS  ) 7 (2 S  , 3  R ) 8 (2  R , 3 S  )yield = 47%; 98% eeyield = 48%; 96% eea Scheme 1.  Reagents and conditions: (a) ( S  , S  )-Co(salen)OAc, (0.5 mol %), THF, H 2 O (0.5 equiv), 0   C, 14 h. OHaOHOOHOMeOHOMeObc 9  anti -10  anti- 6 (2 SR , 3  RS  ) Scheme 2.  Reagents and conditions: (a)  m CPBA, CH 2 Cl 2 , 14 h, 0   C, 88%; (b) camphor sulfonic acid (10 mol %), MeOH; 1 h, 96%; (c) (i) TsCl, Bu 2 SnO (2 mol %), Et 3 N, DMAP(10 mol %), CH 2 Cl 2 , 2 h; (ii) K 2 CO 3 , MeOH, 3 h, 76% (two-steps). OHOMeOHOR'OMeOROHOMeOBnOOOROR' 711  R = H; R' = TBS 12  R = Bn; R' = TBS 13  R = Bn; R' = H 1416  R = Me; R' = Bn 2 R = Me; R' = H 1  R = H; R' = Habcdf ghOOMeOBnePhO 15 Scheme 3.  Reagents and conditions: (a) TBDMSCl, imidazole, CH 2 Cl 2,  0–25   C, 1 h, 90%; (b) NaH, DMF, BnBr, 0–25   C, 2 h, 95%; (c) TBAF, THF, 25   C, 8 h, 91%; (d) IBX, DMSO,2 h, 25   C then TiCl 4 , tributyl allyl stannane, CH 2 Cl 2 ,   78   C, 30 min, 73% (over two-steps); (e) ( E  )-cinnamoyl chloride, py, DMAP, CH 2 Cl 2 , 0–25   C, overnight, 64%; (f) Grubbs’second generation catalyst (10 mol %), CH 2 Cl 2 , reflux, 8 h, 76%; (g) DDQ, CH 2 Cl 2 /H 2 O, 25   C, 16 h, 64%; (h) BBr 3 , CH 2 Cl 2 ,   78   C, 6 h, 71%. I. N. I. N. Chaithanya Kiran et al./Tetrahedron Letters 52 (2011) 438–440  439  out to furnish (+)-8-methoxygoniodiol ( 2 ) in 64% yield. 13 Demeth-ylation of   2  with BBr 3  was successfully performed to afford (+)-goniodiol ( 1 ) in 71% yield. 14 The spectral data of both (+)-8-meth-oxygoniodiol ( 2 ) 17 and (+)-goniodiol ( 1 ) 18 are in complete agree-ment with the reported values. 5,7 In summary, we have developed an efficient and straight-for-ward enantioselective synthesis of two bioactive moleculesnamely (+)-goniodiol ( 1 ) and (+)-8-methoxygoniodiol ( 2 ) with anoverall yield of 5.9% and 8.3%, respectively, that have beenachieved using two-stereocenter Co-catalyzed HKR of racemicepoxide and Lewis acid-mediated diastereoselective allylation of aldehyde. This methodology is also amenable for a viable syntheticroute in the synthesis of other diastereomers  3 – 5  of styryllactonefamily by employing ( R , R )-salen Co(OAc) complex for HKR andBF 3 .OEt 2 , for Lewis acid-mediated diastereoselective allylation,respectively.  Acknowledgments I.N.C.K. and R.S.R. thank CSIR, New Delhi for the award of re-search fellowship and DST (No. SR/S1/OC-72/2006) New Delhi,for financial support. The authors are thankful to Dr. B.D. Kulkarni,Head, CEPD, for his constant support and encouragement. References and notes 1. Jewers, K.; Davis, J. B.; Dougan, J.; Manchanda, A. H.; Blunden, G.; Aye, K.;Wetchapinan, S.  Phytochemistry  1972 ,  11 , 2025.2. Wu, Y. C.; Duh, C. Y.; Chang, F. R.; Chang, G. Y.; Wang, S. K.; Chang, J. J.; McPhail,A. T.; Lee, K. H.  J. Nat. Prod.  1991 ,  54 , 1077.3. Sam, T.; Sew-Yeu, C.; Matsjeh, S.; Gan, E. K.; Razak, D.; Mohamed, A. L. Tetrahedron Lett.  1987 ,  28 , 2541.4. (a) Talapatra, S. K.; Basu, D.; Deb, T.; Goswami, S.; Talapatra, B.  Indian J. Chem.,Sect B  1985 ,  24B , 29; (b) Lan, Y. H.; Chang, F. R.; Liaw, C. C.; Wu, C. C.; Chiang, M.Y.; Wu, Y. C.  Planta Med.  2005 ,  71 , 153.5. Lan, Y. H.; Chang, F. R.; Yu, J. H.; Yang, Y. L.; Chang, Y. L.; Lee, S. J.; Wu, Y. C.  J.Nat. Prod.  2003 ,  66  , 487.6. (a) Tsubuki, M.; Kanai, K.; Honda, T.  J. Chem. Soc., Chem. Commun.  1992 , 1640;(b) Tsubuki, M.; Kanai, K.; Nagase, H.; Honda, T.  Tetrahedron  1999 ,  55 , 2493.7. (a) Surivet, J. P.; Gore, J.; Vatele, J. M.  Tetrahedron Lett.  1996 ,  37  , 371; (b) Mukai,C.; Hirai, S.; Hanaoka, M.  J. Org. Chem.  1997 ,  2 , 6619; (c) Banwell, M. G.; Coster,M. J.; Edwards, A. J.; Karunaratne, O. P.; Smith, J. A.; Welling, L. L.; Willis, A. C.  Aust. J. Chem.  2003 ,  56  , 585; (d) Deligny, M.; Carreaux, F.; Carboni, B.  Synlett  2005 , 1462; (e) Tate, E. W.; Dixon, D. J.; Ley, S. V.  Org. Biomol. Chem.  2006 ,  4 ,1698;(f)Prasad,K.R.;Gholap,S.L. Tetrahedron Lett. 2007 , 48 ,4679;(g)Yadav,J.S.; Premalatha, K.; Harshavardhan, S. J.; Reddy, B. V. S.  Tetrahedron Lett.  2008 , 49 , 6765; (h) Yadav, J. S.; Rao, B. M.; Sanjeevrao, K.; Reddy, B. V. S.  Synlett   2008 ,1039; (i) Favre, A.; Carreaux, F.; Deligny, M.; Carboni, B.  Eur. J. Org. Chem.  2008 ,4900; (j) Yadav, J. S.; Krishna, V. H.; Srilatha, A.; Somaiah, R.; Reddy, B. V. S. Synthesis  2010 , 3004.8. (a) Reddy, R. S.; Chouthaiwale, P. V.; Suryavanshi, G.; Chavan, V. B.; Sudalai, A. Chem. Commun.  2010 ,  46  , 5012; (b) Tokunaga, M.; Larrow, J. F.; Kakiuchi, F.; Jacobsen, E. N.  Science  1997 ,  277  , 936; (c) Tanako, S.; Yanase, M.; Ogasawara, K. Synthesis  1989 , 39.9. Kotkar, S. P.; Sudalai, A.  Tetrahedron: Asymmetry  1738 ,  2006  , 17.10. George, S.; Sudalai, A.  Tetrahedron: Asymmetry  2007 ,  18 , 97.11. Keck, G. E.; Boden, E. P.  Tetrahedron Lett.  1984 ,  25 , 265.12. Ramachandran, P. V.; Chandra, J. S.; Reddy, M. V. R.  J. Org. Chem.  2002 ,  67  , 7547.13. Langille, N. F.; Panek, J. S.  Org. Lett.  2004 ,  6  , 3203.14. Grieco, P. A.; Nishizawa, M.; Burke, S. D.; Marinovic, N.  J. Am. Chem. Soc.  1976 , 98 , 1612.15. Fang, X. P.; Anderson, J. E.; Chang, C. J.; McLaughlin, J. L.; Fanwick, P. E.  J. Nat.Prod.  1991 ,  54 , 1034.16.  Spectral data of (2S,3R)-3-methoxy-3-phenyl-1,2-propanediol  ( 7 ):  ½ a  D25  = +113.95( c   1.16, CHCl 3 ); lit. 8c ½ a  D25  = +113.97 ( c   1.016, CHCl 3 ); 98% ee by chiral HPLCanalysis (Chiralcel OJ-H,  n -hexane/ i PrOH, 86:14, 0.5 mL/min) retention time24.15 (98.92%)and 25.50(1.08%); IR (CHCl 3 ): 720,845, 1065,1125, 1654, 2985,3085, 3465 cm  1 ;  1 H NMR (200 MHz, CDCl 3 ):  d  2.32 (br s, 2H), 3.30 (s, 3H),3.52–3.78 (m, 3H), 4.32 (d,  J   = 9.2 Hz, 1H), 7.33–7.36 (m, 5H);  13 C NMR (50 MHz, CDCl 3 ):  d  57.16, 62.98, 74.53, 85.28, 127.34, 128.11, 128.51, 137.12.Elemental analysis: C 10 H 14 O 3  requires: C, 65.91; H, 7.74%. Found: C, 65.89; H,7.37%.17.  Spectral data of 8-methoxygoniodiol  ( 2 ): mp 98   C (lit. 5 mp 99–101   C);  ½ a  D25  = +23.8 ( c   0.54, CHCl 3 ); lit. 5 ½ a  D25  = +24.2 ( c   0.68, CHCl 3 ); IR (CHCl 3 ): 757, 1057,1109, 1380, 1719, 2909, 3445 cm  1 ;  1 H NMR (200 MHz, CDCl 3 ):  d  2.25 (m, 1H),2.74 (m, 1H), 3.20 (s, 3H), 3.54–3.57 (m, 1H), 4.29 (d,  J   = 8.6 Hz, 1H), 4.74 (ddd,  J   = 12.0, 3.8, 1.9 Hz, 1H), 5.93–5.60 (dd,  J   = 9.6, 2.1 Hz, 1H), 6.74 (ddd,  J   = 9.6,6.3, 2.1 Hz, 1H), 7.30–7.42 (m, 5H);  13 C NMR (50 MHz, CDCl 3 ):  d  26.71, 56.62,73.46, 75.61, 82.30, 119.35, 127.68, 128.16, 138.16, 143.92, 164.87. Elementalanalysis: C 14 H 16 O 4  requires: C, 67.73; H, 6.50%. Found: C, 67.71; H, 6.39%.18.  Spectral data of (+)-goniodiol  ( 1 ):  ½ a  D25  = +73.77 ( c   0.24, CHCl 3 ); lit. 15 ½ a  D25  = +74.4 ( c   0.3, CHCl 3 ) IR (CHCl 3 ): 1035, 1259, 1380, 1690, 3390 cm  1 ;  1 HNMR (200 MHz, CDCl 3 ):  d  2.20 (ddd,  J   = 3.6, 6.8, 16.5 Hz, 2H), 2.80–2.89 (m,2H), 4.10 (t,  J   = 7.8 Hz, 1H), 5.10–5.24 (m, 2H), 6.03 (dd,  J   = 3.6, 7.2 Hz, 1H), 6.94(ddd,  J   = 2.9, 6.4, 8.1 Hz, 1H), 7.27.7.38 (m, 5H);  13 C NMR (50 MHz, CDCl 3 ):  d 26.48, 73.82, 75.06, 76.45, 121.03, 126.5, 128.47, 129.01, 138.51, 145.45,163.18. Elemental analysis: C 13 H 14 O 4  requires: C, 66.66; H, 6.02%. Found: C,66.62; H, 6.01%.440  I. N. I. N. Chaithanya Kiran et al./Tetrahedron Letters 52 (2011) 438–440
Search
Similar documents
View more...
Related Search
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks