Synthesis of Functionalized 2-Alkylidene-tetrahydrofurans Based on a [3+2] Cyclization/Bromination/Palladium(0) Cross-Coupling Strategy

Effective Synthesis of a Novel Tetrahydrofuran Containing Triterpenoid: 5′(Z)-Benzylidene-tetrahydrofurano[3,2-b]lup-20(29)-en-28-oate

The title compound 5′(Z)-benzylidene-tetrahydrofurano[3,2-b]lup-20(29)-en-28-oate was synthesized with high chemo-, regio-, and stereoselectivity by 5-exo-dig cycloisomerization of methyl 2α-phenylpropynyl-3-oxolup-20(29)-en-28-oate with use of KN(SiMe3)2-DME. The novel betulinic acid derivative was fully characterized by conventional analytical methods and all proton and carbon signals have been completely assigned by 2D-NMR experiments.

Stereoselective synthesis of (Z)-alpha-halo-alpha,beta-unsaturated esters, and amides from aldehydes and trihaloesters or amides promoted by manganese

Preliminary results of a Mn-promoted sequential process directed toward the stereoselective synthesis of different (Z)-alpha-halo-alpha,beta-unsaturated compounds are described.