A temporary stereocentre approach for the asymmetric synthesis of chiral cyclopropane-carboxaldehydes
作者:Matt Cheeseman、Iwan R. Davies、Phil Axe、Andrew L. Johnson、Steven D. Bull
DOI:10.1039/b908600e
日期:——
A novel way of combining chiral auxiliaries and substrate directable reactions is described that employs a three-step sequence of aldol/cyclopropanation/retro-aldol reactions for the asymmetric synthesis of enantiopure cyclopropane-carboxaldehydes. In the first step, reaction of the boron enolate of (S)-N-propionyl-5,5-dimethyl-oxazolidin-2-one with a series of α,β-unsaturated aldehydes affords their
Enantio- and diastereocontrolled conversion of chiral epoxides to trans-cyclopropane carboxylates: application to the synthesis of cascarillic acid, grenadamide and <scp>l</scp>-(−)-CCG-II
作者:Pradeep Kumar、Abhishek Dubey、Anand Harbindu
DOI:10.1039/c2ob25622c
日期:——
An efficient high yielding improved method for the enantio- and diastereoselective cyclopropanation of chiral epoxides using triethylphosphonoacetate and base (Wadsworth–Emmons cyclopropanation) is reported. The utility of this protocol is illustrated by concise and practical synthesis of cascarillic acid, grenadamide and L-(−)-CCG-II, a cyclopropane containing natural products.
Sequential cross-metathesis/cyclopropanation: short syntheses of (+/−)-cascarillic acid and (+/−)-grenadamide
作者:Hani Salim、Olivier Piva
DOI:10.1016/j.tetlet.2007.01.152
日期:2007.3
The total synthesis of (+/−)-cascarillic acid has been achieved by a sequential cross-metathesis/Simmons–Smithcyclopropanation between, respectively, 1-octene with an appropriate unsaturated carboxylic acid. In parallel, a direct access to grenadamide was developed from 1-nonene with a readily available unsaturated amide. In both cases, the chemical yields were high (up to 98%) and the E/Z ratio was
An Efficient Asymmetric Synthesis of Cascarillic Acid
作者:Steven Bull、Matt Cheeseman
DOI:10.1055/s-2006-939690
日期:——
An efficient six-step asymmetric synthesis of the cyclopropane containing natural product cascarillic acid in 41% overall yield is described. The key synthetic steps involve the use of a temporary stereogenic hydroxyl group to control the facial selectivity of a directed cyclopropanation reaction and its subsequent removal via a retro-aldol reaction.