Addition of the in situ generated Schwartz reagent to widely available isocyanates constitutes a chemoselective, high-yielding, and versatile approach to the synthesis of variously functionalized formamides. Steric and electronic factors or the presence of sensitive functionalities (esters, nitro groups, nitriles, alkenes) do not compromise the potential of the method. Full preservation of the stereochemical information contained in the starting materials is observed. The use of formamides in the nucleophilic addition of organometallic reagents (Chida-Sato allylation, Charette-Huang addition to imidoyl triflate activated amides, Matteson homologation of boronic esters) is briefly investigated.

The regio-and stereoselective addition of germanium and zinc across the CC triple bond of nitrogen-, sulfur-, oxygen-, and phosphorous-substituted terminal and internal alkynes is achieved by reaction with a combination of R 3 GeH and Et 2 Zn. Diagnostic experiments support a radical-chain mechanism and the -zincated vinylgermanes that show exceptional stability are characterized by NMR spectroscopy and X-ray crystallography. The unique feature of this new radical germylzincation reaction is that the C(sp 2)-Zn bond formed remains available for subsequent in situ Cu(I)-or Pd(0)-mediated CC or C-heteroatom bond formation with retention of the double bond geometry. These protocols offer a modular access to elaborated tri-and tetrasubstituted vinylgermanes decorated with heteroatom substituents  to germanium that are useful for the preparation of stereodefined alkenes. Additional data and discussion, experimental details, NMR spectra for new compounds, and X-ray crystal structures (PDF) Crystallographic information files (CIF)