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 and B via a tethered oxa-Michael approach
作者:S. Chandrasekhar、Ch. Rambabu、T. Shyamsunder
DOI:10.1016/j.tetlet.2007.05.026
日期:2007.7
A stereocontrolled total synthesis of aculeatins A and B has been achieved in eight steps and in 15% overall yield. The key feature of this synthetic approach is the application of a Marouka allylation and tethered intramolecular oxa-Michael reaction to install the required stereocentres on the tetrahydropyran ring.
Total Synthesis of Aculeatins A and B from L-Malic Acid
作者:Jhillu S. Yadav、Yerragorla Gopala Rao、Dandekar Chandrakanth、Kontham Ravindar、Basi V. Subba Reddy
DOI:10.1002/hlca.201000084
日期:2010.12
moiety with appropriate configuration was accomplished from the commercially available L‐malic acid. The key steps in this synthesis are the Barbier allylation, LiAlH4/LiI‐mediated syn‐stereoselective 1,3‐asymmetric reduction, and phenyliodine bis(trifluoroacetate) (=[bis(trifluoroacetoxy)iodo]benzene; PIFA) mediated oxidative spirocyclization.
A modular total synthesis of aculeatins A, B, E, F and 6-epi-aculeatins E, F
作者:C.V. Ramana、Sunil Kumar Pandey
DOI:10.1016/j.tet.2009.10.058
日期:2010.1
The totalsynthesis of aculeatins A, B, E and F confirming the assigned absolute configuration of recently isolated aculeatins E and F is documented. A convergent approach has been designed by the addition of both the terminal units (phenol and side chain) at an advanced stage. The central 1,3,5-triol unit with the requisite stereochemistry was prepared from the commercially available α-d-glucoheptonic-γ-lactone