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
Stereochemistry of intramolecular free-radical cyclization reactions
Journal ArticleDOI
Catalytic asymmetric allylation of 3,4-dihydroisoquinolines and its application to the synthesis of isoquinoline alkaloids.
Michiko Miyazaki,Nami Ando,Keita Sugai,Yuki Seito,Hiromi Fukuoka,Takuya Kanemitsu,Kazuhiro Nagata,Yuki Odanaka,Kazuo T. Nakamura,Takashi Itoh +9 more
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
Dimethyl sulfoxide-trifluoroacetic anhydride. New reagent for oxidation of alcohols to carbonyls
Journal ArticleDOI
Free-radical cyclization of bromo acetals. Use in the construction of bicyclic acetals and lactones
Journal ArticleDOI
Homolytic carbocyclization by use of a heterogeneous supported organotin catalyst. A new synthetic route to 2-alkoxytetrahydrofurans and .gamma.-butyrolactones
Journal ArticleDOI
Kinetics and mechanism of some vinyl radical cyclisations
TL;DR: In this paper, the vinyl radicals 2a, 2b and 11 each undergo fast exo ring closure to give 5a, 5b, and 12, the first two of which readily rearrange to ringexpanded radicals.
Related Papers (5)
Catalytic iron-mediated enediene carbocyclizations : the enantioselective synthesis of a homologue of the alkaloid (-)-protoemetinol
James M. Takacs,Scott C. Boito +1 more