Stereoselective Three-Carbon and Two-Carbon Elongation of the Carbon Chain in N-Boc-Protected α-Aminoacylsilanes: An Entry to Functionalized β-Amino Alcohols and to Statine Analogues
A Highly Stereoselective Formal Synthesis of Hapalosin
作者:B. Reddy、Harish Kumar、A. Reddy、J. Yadav
DOI:10.1055/s-0033-1338952
日期:——
A flexible and highly diastereoselective formal synthesis of hapalosin, a cyclodepsipeptide isolated from the blue green alga Hapalosiphon welwitschii and having multidrug-resistance-reversing activity is described. The synthetic route involves the addition of organometallic reagent to N-tert-butanesulfinylimine, Jung nonaldol aldol reaction, and Yamaguchi esterification as key steps.
Selective reductions of oxazolidinones: New protocol for diastereoselective synthesis of vicinal amino alcohols
作者:G.Vidyasagar Reddy、G.Venkat Rao、D.S. Iyengar
DOI:10.1016/s0040-4039(99)00265-8
日期:1999.3
Selective reductions of oxazolidinones using sodium borohydride and their application to the diastereoselective synthesis of vicinal amino alcohols are described.
The intermediates generated by DIBALH reduction of α-aminoacidesters undergo condensation without racemization with silylketeneacetals and allylstannane in the presence of Lewis acid to afford the corresponding β-hydroxy esters and homoallylic alcohols in good yields while achieving high syn selectivity via an aluminum-assisted chelation control.
Titanium tetrachloride mediated addition of allyltrimethylsilane to chiral acetals derived from (S)-α-amino aldehydes and (+)-(2S,4S)-pentane-2,4-diol gave the anti-2-amino alcohol derivatives with considerably high diastereoselectivity. On the other hand, the same reaction by the use of acetals obtained from (−)-(2R,4R)-pentane-2,4-diol gave the products of opposite stereochemistry series as major