Diastereodivergent Strategies for the Synthesis of Homochiral Aculeatins
摘要:
We report concise and stereocontrolled syntheses of aculeatins (-)-A, (+)-B, (+)-D, and (+)-6-epi-D. Diastereodivergent 1,3-inductions in Mukaiyama aldol coupling contribute to reduce steps and to increase flexibility with reactants having sterically restricted proximal substituents (i.e., CH2), involving either a good anti or a moderate syn 1,3-induction, depending on the nature of protecting group (P). In addition, the 3,5-syn-diol-ketone resulting from concomitant deprotection of the beta-alkoxy (Tr = trityl) group proves to be remarkably stable whereas the 3,5-anti diastereoisomer cyclizes spontaneously to the corresponding tetrahydropyran hemiketal, thus enabling a useful and facile separation. The second part of our study is devoted to improving the yield and the diastereoselectivity of the final phenolic oxidation reaction leading to aculeatins.
Total Synthesis of Aculeatins A, B and D and 6-epi-Aculeatin D via an Asymmetric Aldol Approach
作者:Biswanath Das、Lingaiah Maram
DOI:10.1055/s-0033-1340866
日期:——
Abstract Simple and efficient stereoselectivetotalsyntheses of aculeatins A, B and D and 6-epi-aculeatin D starting from 1-tetradecanal have been accomplished. The synthesis is based on the Crimmins aldol reaction involving a chiral auxiliary. Simple and efficient stereoselectivetotalsyntheses of aculeatins A, B and D and 6-epi-aculeatin D starting from 1-tetradecanal have been accomplished. The
Total Synthesis of (+)-Aculeatin D and (+)-6-epi-Aculeatin D
作者:J. Yadav、K. Rao、K. Ravindar、B. Reddy
DOI:10.1055/s-0029-1218546
日期:2010.1
synthesis of spiroketal natural product (+)-aculeatin D and unnatural (+)-6-epi-aculeatin D has been accomplished. Sharpless kinetic resolution of secondary allylic alcohol and phenyliodine(III) bis(trifluoroacetate) (PIFA)-mediated oxidative spirocyclization were used as key steps in this synthesis.
Enantioselective synthesis and absolute configurations of aculeatins A, B, D, and 6-epi-aculeatin D
作者:Paula Álvarez-Bercedo、Eva Falomir、Miguel Carda、J.A. Marco
DOI:10.1016/j.tet.2006.07.076
日期:2006.10
The three naturally occurring, bioactive spiroacetals aculeatins A, B, and D, as well as the non-natural 6-epi-aculeatin D have been synthesized for the first time in enantiopure form using an asymmetric allylation as the only chirality source. A further key step was a stereoselective aldol reaction with remote induction. The absoluteconfigurations of the natural products have been established and
A Chiron Approach to the Total Synthesis of (+)-Aculeatin D
作者:Zhi-Bin Zhen、Jian Gao、Yikang Wu
DOI:10.1021/jo801296x
日期:2008.9.19
A synthesis of natural aculeatin D has been achieved, with the key stereogenic centers taken from inexpensive and readily available D-xylose. In elaboration of D-xylose into a desired form readily applicable in synthesis a previously misinterpreted and overlooked abnormal selectivity in hydroxyl protection was noticed and exploited. Protocols were developed for monotosylation of a triol insoluble in
Polyol Synthesis with β-Oxyanionic Alkyllithium Reagents: Syntheses of Aculeatins A, B, and D
作者:Viengkham Malathong、Scott D. Rychnovsky
DOI:10.1021/ol901623h
日期:2009.9.17
route was developed. The β-phenylthio alcohols were prepared from opticallypure oxiranes. Deprotonation and reductivelithiationgenerated the key intermediate, a β-oxyanionic alkyllithium reagent. Addition to a Weinreb amide produced the β-hydroxy ketone in >90% yield using only 1.5 equiv of the phenylthio alcohol. Stereoselective reduction of the ketone led to either the syn- or anti-1,3-diol. This simple