Studies Directed toward the Construction of the Polypropionate Fragment of Superstolide A
摘要:
Highly stereoselective approaches directed toward the synthesis of the C18-C27 fragment of superstolide A are disclosed taking ketone 6 and aldehyde 7 as the only sources of chirality.
The dynamic resolution of racemic acyclic α-hydroxy ketone derivatives is accomplished using an optically active host compound, TADDOL, under basic conditions to give the corresponding optically active ketones.
Highly Stereoselective Aldol Reactions of Titanium Enolates from Lactate-Derived Chiral Ketones
作者:Joan G. Solsona、Pedro Romea、Fèlix Urpí、Jaume Vilarrasa
DOI:10.1021/ol0274054
日期:2003.2.1
[reaction: see text] Highly stereoselective titanium-mediated aldolreactions based on lactate-derived ketones are reported. The stereochemical outcome of the process depends on the protecting group (PMB or Bn) and the Lewis acid (i-PrOTiCl(3) or TiCl(4)) used in the enolization step, the corresponding anti-syn or syn-syn aldols being prepared in high yields and with diastereomeric ratios up to 99:1
Double Stereodifferentiating Aldol Reactions Based on Chiral Ketones Derived from Lactic Acid: Synthesis of C1-C6 Fragment of Erythronolides
作者:Pedro Romea、Fèlix Urpí、Joan G. Solsona、Joaquim Nebot
DOI:10.1055/s-2004-831332
日期:——
Highly stereoselective titanium-mediated aldol additions of ethyl ketones derivedfromlacticacid to α-methyl-β-OTBDPS chiral aldehydes are documented. One of these double stereodifferentiating processes represents the key step of a straightforward and efficient synthetic approach to the C1-C6 fragment of erythronolides.
The acylation reaction of organolithium reagents with pyrrolidine-derived α-benzyloxy and α-silyloxy carboxamides provides a simple and high-yielding method for the preparation of enantiopure α-benzyloxy and α-silyloxy ketones.