Non-Pd transition metal-catalyzed hydrostannations: Bu3SnF/PMHS as a tin hydride source
作者:Robert E. Maleczka、Banibrata Ghosh、William P. Gallagher、Aaron J. Baker、Jill A. Muchnij、Amy L. Szymanski
DOI:10.1016/j.tet.2013.02.064
日期:2013.5
and rhodium catalyzed alkyne hydrostannations using in situ generated Bu3SnH were studied. In most cases, Bu3SnF+polymethylhydrosiloxane (PMHS) performed well as the in situ source of Bu3SnH. In contrast, the combination of Bu3SnCl/KFaq/PMHS, which had witnessed earlier success in Pd-catalyzed hydrostannation reactions, proved less employable in alkyne hydrostannations mediated by these metals.
Rhodium complexes (RhClL3, RhCl(CO)L2, [RhCl(COD)]2; L=PPh3) catalyze hydrostannation of terminal acetylenes (RC≡CH; R=Ph, Me3Si, R1OC(R2)(R3), and R1OCH2CH2; R1=THP, OAc; R1, R2=H, Me) with Bu3SnH to produce R(Bu3Sn)C=CH2 selectively. Other transition metal complexes [MCl2L2(M=Ni, Pd, Pt, Co)] are also active for the hydrostannation, but with less selectivity.
A Straightforward Approach towards Piperidines via Stille Coupling and Subsequent 1,4-Addition of Amines
作者:Uli Kazmaier、Sandra Dörrenbächer、Sven Ruf
DOI:10.1055/s-2006-926246
日期:——
Substituted 4-piperidones are easily obtained from alkynes via molybdenum-catalyzed regioselective hydrostannation and subsequent Stille-coupling of the vinyl stannanes obtained with α,β-unsaturated acyl chlorides. The resulting divinylketones can undergo a double 1,4-addition of amines giving rise to the required 4-piperidones. The best results are obtained if the Stille couplings and the 1,4-additions are combined in a one-pot procedure.