Pd-catalyzed cross-coupling of functionalized organozinc reagents with thiomethyl-substituted heterocycles.

Various thiomethyl-substituted N-heterocycles (pyridines, pyrimidines, pyrazines, pyridazines, triazines, benzothiazoles, benzoxazoles, pyrazoles, benzindazoles, quinazolines, etc.) undergo smooth Pd-catalyzed cross-coupling reactions with functionalized aryl-, heteroaryl-, benzylic-, and alkylzinc reagents using Pd(OAc)(2)/S-Phos as the catalytic system mostly at 25 degrees C. No copper salt is required to perform these reactions.

Synthesis of fully substituted pyrazoles via regio- and chemoselective metalations.

The full functionalization of the pyrazole ring was achieved by successive regioselective metalations using TMPMgCl x LiCl and TMP(2)Mg x 2 LiCl. Trapping with various electrophiles led to trisubstituted pyrazoles. An application to the synthesis of the acaricide Tebufenpyrad is reported.

Selective mono- and 1,2-difunctionalisation of cyclopentene derivatives via Mg and Cu intermediates.

A single Br/Mg exchange of 1,2-dibromocyclopentene with iPrMgCl LiCl provides the corresponding beta-bromocyclopentenylmagnesium reagent, which can then be reacted with various electrophiles (yields: 65-82 %). In the presence of a secondary alkylmagnesium halide and Li2CuCl4 (2 mol %), these 2-bromoalkenylmagnesium compounds undergo bromine substitution and can then further react with electrophiles to give 1,2-difunctionalised cyclopentenes (63-79 %). The mechanism of this process is discussed.