scispace - formally typeset
Journal ArticleDOI

Asymmetric total synthesis of(–)-protoemetinol,(–)-protoemetine,(–)-emetine, and (–)-tubulosine by highly stereocontrolled radical cyclisations

Reads0
Chats0
TLDR
Both enantiomers of the menthyl halfesters (10) and (23) of ethylmalonic acid were converted into (+)-(4S,5R)-4-(2-benzyloxyethyl)-5-ethyl-3,4,5,6-tetrahydro-2-pyrone (18) as discussed by the authors.
Abstract
Both enantiomers of the menthyl half-esters (10) and (23) of ethylmalonic acid were converted into(+)-(4S,5R)-4-(2-benzyloxyethyl)-5-ethyl-3,4,5,6-tetrahydro-2-pyrone (18). A mixture of the trans-(18) and cis-lactones (19) in a ratio of ca. 4 : 1 was prepared by way of radical cyclisation of the (E)-α,β-unsaturated esters (16), while the former (18) was synthesised with high stereoselection by the cyclisation of the (Z)-esters (26). The lactone (18) was enantioselectively transformed into (–)-protoemetimol (5) and (–)-protoemetine (4), correlated to (–)-emetine (1) and (–)-tubulosine (3).

read more

Citations
More filters
Journal ArticleDOI

Catalytic asymmetric allylation of 3,4-dihydroisoquinolines and its application to the synthesis of isoquinoline alkaloids.

TL;DR: A catalytic asymmetric allylation of 3,4-dihydroisoquinoline was carried out with allyltrimethoxylsilane-Cu as the nucleophile and the allyl adduct obtained was applied to the synthesis of several isoquinoline alkaloids such as crispine A and homolaudanosine.
Journal ArticleDOI

A stereodivergent strategy for the preparation of corynantheine and ipecac alkaloids, their epimers, and analogues: efficient total synthesis of (-)-dihydrocorynantheol, (-)-corynantheol, (-)-protoemetinol, (-)-corynantheal, (-)-protoemetine, and related natural and nonnatural compounds.

TL;DR: The potential of this strategy is demonstrated in the synthesis of biologically interesting natural product analogues not accessible through synthetic elaboration of alkaloid precursors available from nature, for example, thieno[3,2-a]quinolizidine derivatives.
Journal ArticleDOI

Intramolecular reductive cyclisations using electrochemistry: development of environmentally friendly synthetic methodologies

TL;DR: In this article, a review summarises electrochemical reductive intramolecular cyclisations, including transition-metal catalysed reactions, and presents some selected examples of organic halide electroreductions with further intramerolecular coupling reactions, carbonyl group reductions with further coupling, and intramerial cyclisations involving electrogenerated bases.
References
More filters
Journal ArticleDOI

Total synthesis of (±)-alliacolide

TL;DR: A total synthesis of the unique epoxy-lactone alliacolide, featuring a novel, stereoselective intramolecular radical cyclisation onto an enolic double-bond, viz (13) → (14), as a key step, is described in this paper.
Journal ArticleDOI

1,2-Asymmetric induction in intramolecular Michael reaction. A novel and enantioselective route to (+)-Geissman lactone

TL;DR: The Horner-Emmons reaction of the hemiacetal (19), derived from L-(+)-diethyl tartrate, was found to give the pyrrolidine (21) via an intramolecular Michael reaction as a mixture of diastereoisomers which, after treatment with ethanethiol and boron trifluoride-diethy ether, was converted into the lactone (22) and the ester (23) as mentioned in this paper.
Related Papers (5)