Synthesis of the C-1 sidechain of the squalestatins and zaragozic acid A
作者:Jack G. Parsons、Mark A. Rizzacasa
DOI:10.1016/0040-4039(94)88298-3
日期:1994.10
A synthesis of a protected C-1 side chain precursor (2) of the anti-cholesteremic agents the squalestatins and zaragozicacid A has been achieved in 9 steps from 1,4-butanediol. The key transformations involve a one pot oxidation/α-methylenation sequence to provide the α,β-unsaturated aldehyde 4 and subsequent asymmetric aldol reaction to introduce the C-4′ and C-5′ stereocentres.
Addition of kinetic boron enolates generated from β-alkoxy methyl ketones to aldehydes. Density functional theory calculations on the transition structures
作者:Luiz C. Dias、Sávio M. Pinheiro、Vanda M. de Oliveira、Marco A.B. Ferreira、Cláudio F. Tormena、Andrea M. Aguilar、Julio Zukerman-Schpector、Edward R.T. Tiekink
DOI:10.1016/j.tet.2009.08.042
日期:2009.10
of 1,5-anti stereoinduction are obtained in boron enolate aldol reactions of 1,2-syn β-alkoxy methyl ketones with achiral aldehydes, when the β-alkoxy protecting group is part of a benzylidene acetal. We have also investigated the effects of the ligands on boron, the α-, β-, and γ-substituents and the β-alkoxy protecting group on the boron enolates, using density functional theory (B3LYP) and Møller–Plesset
Synthesis of the C1-C17 Macrolactone of Tedanolide
作者:Markus Kalesse、Jorma Hassfeld、Ulrike Eggert
DOI:10.1055/s-2005-865302
日期:——
The vinylogous Mukaiyama aldol reaction is a useful method to build up complex polyketide structures. It is successfully employed in the synthesis of the C1-C17 macrolactone of tedanolide, a highly cytotoxic marine natural product. These studies present a practical approach toward the total synthesis of tedanolide; it is pursued using the appropriate C13-C23 segment that is introduced by a pivotal aldol reaction to join both hemispheres.
Sequencing cross-metathesis and non-metathesis reactions to rapidly access building blocks for synthesis
作者:Gopal Sirasani、Tapas Paul、Rodrigo B. Andrade
DOI:10.1016/j.tet.2011.01.080
日期:2011.3
The olefin cross-metathesis reaction has been sequenced with four common organic transformations in a one- or two-pot manner to rapidly access useful building blocks. Those reactions are: (1) phosphorus-based olefination (e.g.. Wittig and Horner-Wadsworth-Emmons); (2) hydride reduction; (3) Evans propionate aldol reaction; (4) Brown allyl- and Roush crotyl-boration. The products of these reactions include stereodefined 2,4-dienoates, trans allylic alcohols, syn-propionate aldols, and chiral non-racemic homoallylic alcohols, respectively. Many of these intermediates have been carried further to natural products, demonstrating the utility of the methodology. (C) 2011 Elsevier Ltd. All rights reserved.