Enantioselective total syntheses of pumiliotoxin B and pumiliotoxin 251D. A general entry to the pumiliotoxin A alkaloids via stereospecific iminium ion-vinylsilane cyclizations
work as organocatalysts for Mitsunobureactions because they provide ethyl 2-arylazocarboxylates through aerobic oxidation with a catalytic amount of iron phthalocyanine. First, ethyl 2-(3,4-dichlorophenyl)hydrazinecarboxylate has been identified as a potent catalyst, and the reactivity of the catalyticMitsunobureaction was improved through strict optimization of the reaction conditions. Investigation
A catalytic Mitsunobu reaction system is described in which the azo reagent is used as an organocatalyst and iodosobenzene diacetate is used as the stoichiometric oxidant. In this system, iodosobenzene diacetate oxidizes the formed hydrazine byproduct to regenerate the azo reagent. Yields obtained in the catalytic reactions using a variety of carboxylic acids and alcohols were slightly lower than those
Organocatalytic Mitsunobu Reactions with 3,5-Dinitrobenzoic Acid
作者:Patrick Toy、Tracy But、Jinni Lu
DOI:10.1055/s-0029-1219795
日期:2010.4
A second generation procedure for organocatalytic Mitsunobu reactions using 3,5-dinitrobenzoicacid as the pro-nucleophile has been developed. The increased acidity of this acid compared to 4-nitrobenzoic acid, which was used in the original procedure, allowed for higher isolated yields of the desired products and eliminated formation of undesired acetate byproducts.
Mitsunobu Reactions Catalytic in Phosphine and a Fully Catalytic System
作者:Joseph A. Buonomo、Courtney C. Aldrich
DOI:10.1002/anie.201506263
日期:2015.10.26
overcome both of these shortcomings. Herein we report a protocol that is catalytic in phosphine (1‐phenylphospholane) employing phenylsilane to recycle the catalyst. Integration of this phosphinecatalytic cycle with Taniguchi’s azocarboxylate catalyticsystem provided the first fullycatalyticMitsunobureaction.
2-Arylazocarboxylate and 2-arylazocarboxamide derivatives can serve as replacements of typical Mitsunobu reagents such as diethylazodicarboxylate. A systematic investigation of the reactivity and physical properties of those azo compounds has revealed that they have an excellent ability as Mitsunobu reagents. These reagents show similar or superior reactivity as compared to the known azo reagents