Palladium-catalysed annulation reaction of allenyltins with beta-iodo vinylic acids: selective synthesis of alpha-pyrones

Palladium-catalysed regio- and stereoselective annulation of allenyl stannanes by beta-iodo vinylic acids gives the corresponding alpha-pyrones in high yields. This annulation most probably proceeds through a Stille reaction/cyclisation sequence

An Efficient Synthesis of New 7-Trifluoromethyl-2,5-disubstituted Pyrazolo 1,5-a pyrimidines

International audienceA novel two-step synthesis of trifluoromethylated 3,5-disubstituted pyrazolo[1,5- a ]pyrimidines is reported from 3-aminopyrazoles and ethyl 4,4,4-trifluorobut-2-ynoate. The synthetic route begins with the one-pot synthesis of 7-trifluoromethylated pyrazolo[1,5- a ]pyrimidin-5-ones by condensation of 3-aminopyrazoles with a fluorinated alkyne. The products obtained are used as building blocks to synthesize directly, with excellent yields via C-O bond activation, a library of new fluorinated 3,5-disubstituted pyrazolo[1,5- a ]pyrimidines of biological interest. This operation efficiently allows C-C, C-N and C-S bond formation

Synthesis and Reactivity of beta,gamma-Dihalogenated Unsaturated Acids: Application to the Synthesis of 4-Substituted 5H-Furan-2-ones

International audiencebeta,gamma-Dihalogenated unsaturated acids were prepared regio- and stereoselectively from allenic acid, and some aspects of their reactivities were studied

Copper-mediated cross-coupling of functionalized arylmagnesium reagents with functionalized alkyl and benzylic halides

Functionalized arylmagnesium halides, prepared via an iodine−magnesium exchange, undergo a smooth cross-coupling reaction with functionalized primary alkyl iodides and benzylic bromides in the presence of CuCN·2LiCl, either in stoichiometric (with trimethyl phosphite as an additive) or catalytic quantities

Preparation of polyfunctional heterocycles using highly functionalized aminated arylmagnesium reagents as versatile scaffolds

Functionalized Grignard reagents, derived from readily available o-iodoaniline derivatives and obtained via a straightforward iodine−magnesium exchange, can be used to prepare a wide range of polyfunctional indoles, quinolines, and quinazolinones

Total synthesis of N¹⁴-desacetoxytubulysin H

Equation presented The N14-desacetoxy analogue of tubulysin H was prepared in 20 steps and 2.1% overall yield. Our strategy features a thiazole anion addition to assemble the tubuvaline residue at the C(10)-C(11) bond, as well as acylations at N5, N14, and N 17. This iterative coupling approach, as well as the removal of the labile N,O-acetal at N14, enables the synthesis of analogues for detailed studies of structure-activity relationships in this family of potent tubulin disrupters. © 2007 American Chemical Society