Copper(I) triflate catalyzes the transformation of α-[(2-alkynyl)oxy]silyl-α-diazoacetates 1a–g into 1,2-bis(2,5-dihydro-1,2-oxasilol-4-yl)ethenes 2 and/or 2H-1,2-oxasilines 3. With rhodium(II) perfluorobutyrate as catalyst, 1a–e furnish only 3 but no 2. Bicyclic 2-methoxyfurans 6 are formed when 1a,c,e (containing terminal alkyne functions) are treated with catalytic amounts of copper(I) chloride
The synthesis of two types of so far unknown title compounds is described. Carbene complexes LnMC(R)OSiR2C(N2)COOMe [LnM(OC)5W (3), (OC)5Cr (4), (OC)5Mo (5), (MeCp)(OC)2Mn (6)] were obtained from the corresponding acyl metalates by electrophilic (diazomethyl)silylation. Similarly, (diazomethyl)silylation of lithiated dicarbonyl(η5-methylcyclopentadienyl)(1-ethoxyethylidene)manganese yielded a manganese