Chapter 49 - Compounds with six-membered heterocyclic rings containing one or more unusual hetero atoms together with nitrogen or elements of group VI

Abstract

Publisher Summary This chapter discusses the compounds with six-membered heterocyclic rings containing one or more unusual hetero atoms together with nitrogen or elements of group VI. Boron compounds are presented—dioxaborins and oxathiaborins that include benzo-[1,3,2]-dioxaborins, benz-[3,1,2]-oxathiaborins; dioxaborins bearing another unusual heteroatom, such as 1,3,4,2-dioxasilaborins, 1,3,5,2-dioxaphosphaborinanes; oxadiborins, diazaborines, azadiphosphaborines; tetrazaborines; azadiborines; diazadiborines, and triazadiborines. The chapter also presents silicon, germanium, tin and lead compounds, such as oxa-silins, -germanins, -stannins, and related compounds; perhydro-1,2-oxa-and-thia-silins and –stannins; perhydro-1,3-oxasilins, and the sulfur, selenium and tellurium analogues; dioxa-germanins, -stannins, and plumbins, and their thia analogues; oxadisilins, dioxadisilins, and germanins. The synthesis, structure, and reactions of these different compounds are also discussed. The reaction of heterocyclic aminoboranes with phenyl isocyanate offers a convenient route to large ring organoboranes via ring-expansion. Interest in the possible existence of extended π-interactions between vacant 3d orbitals on silicon and an adjacent π-system has prompted attempts to prepare members of the 1,2-oxasilin system. Insertion of benzaldehyde into the silicon- (or germanium)-phosphorus bond of the four-membered ring compound gives rise to the six-membered ring compound as mixtures of diastereoisomers.