Ring Closing Metathesis for the Asymmetric Synthesis of (S)-Homopipecolic Acid, (S)-Homoproline and (S)-Coniine
作者:Stephen G. Davies、Keiji Iwamoto、Christian A. P. Smethurst、Andrew D. Smith、Humberto Rodriguez-Solla
DOI:10.1055/s-2002-32580
日期:——
Diastereoselective conjugate addition of lithium (S)-N-allyl-N-α-methylbenzylamide to α,β-unsaturated esters or Weinreb amides, followed by ring closing metathesis is used to afford the cyclic β-amino acids (S)-homopipecolic acid and (S)-homoproline and the amine (S)-coniine in high ee.
The preparation of chiral pyrrolidine and piperidine β-enamino esters starting from ω-halogeno β-keto esters, their diastereoselective reduction and the subsequent cleavage of the chiralauxiliary are described.
Convenient Multigram Synthesis of (<i>R</i>)-Homopipecolic Acid Methyl Ester
作者:Matthias Breuning、Melanie Steiner
DOI:10.1055/s-2006-926419
日期:2006.4
(R)-Homopipecolic acidmethylester has been prepared on a multigram scale from 3,4-dihydro-2H-pyran in five steps and 36% overall yield. The stereochemistry was introduced via an asymmetric Michael addition and a fractional crystallization.
Total Synthesis of (−)-Lasubine II by the Conjugate Addition and Intramolecular Acylation of an Amino Ester with an Acetylenic Sulfone
作者:Thomas G. Back、Michael D. Hamilton
DOI:10.1021/ol0258482
日期:2002.5.1
[reaction: see text] The conjugate addition of methyl (S)-(2-piperidyl)acetate (3) to 2-(3,4-dimethoxyphenyl)-1-(p-toluenesulfonyl)ethyne (4), followed by LDA-promoted intramolecularacylation, stereoselective reduction, and desulfonylation, afforded (-)-lasubine II.
Chemoenzymatic approach to enantiopure piperidine-based β-amino esters in organic solvents
作者:Arto Liljeblad、Hanna-Maija Kavenius、Petri Tähtinen、Liisa T. Kanerva
DOI:10.1016/j.tetasy.2007.01.027
日期:2007.2
This research concentrates on the enantioselectivities of lipase-catalysed reactions with methyl esters of 2-piperidylacetic acid and 3-piperidinecarboxylic acid derivatives. N-Acetylated 2-piperidylacetic acid methyl ester displayed good enantioselectivity (E = 66) in a 1:1 mixture of diisopropyl ether and butyl butanoate in the presence of lipase PS-C IT from Burkholderia cepacia. The reaction is known as interesterification with butyl butanoate rather than alcoholysis with the butanol, because butyl butanoate has to be first hydrolysed or go through alcoholysis with MeOH in order to release butanol. Other N-protective groups (Boc, Ns, Fmoc and Bzn) gave excellent en anti oselectivity (E > 200) under the same conditions, and a gram-scale resolution was performed with N-Boc-2-piperidylacetic acid methyl ester. Reaction with a 3-piperidylcarboxylic acid derivative took place with disappointingly low enantioselectivity (E = 4), with Candida antarctica lipase B being the best of the lipases screened. (c) 2007 Elsevier Ltd. All rights reserved.