Eight-membered Rings with Two Heteroatoms 1,2. In Comprehensive Heterocyclic Chemistry III, AR Katritzky, CA Ramsden, EFV Scriven and RJK Taylor, Eds.; Elsevier: Oxford

This chapter deals with heterocine rings with two heteroatoms in a 1,2-relationship, namely 1,2-diazocine, 2H-1,2-oxazocine, 2H-1,2-thiazocine, 1,2-dioxocin, 1,2-oxathiocin, and 1,2-dithiocin. This chapter covers the literature from 1996 to 2006 and also reports those articles published in 1995 which were not reported in CHEC-II(1996). In this edition, in addition to the uncondensed derivatives, eight-membered 1,2-heterocycles fused to five-, six-, and seven-membered carbocycles or heterocycles are covered, although in one case a four-membered fused cycle was occasionally reported. Bridged heterocines, which actually constitute the majority of the compounds reported, are covered as well. The main change in this chapter, with respect to CHEC-II(1996), is related to the “Theoretical Methods” section. Such a section in CHEC-II(1996) was a unique section, placed immediately after the introduction, and it dealt with all the classes of eight-membered heterocycles with two heteroatoms. In this edition, each paragraph dealing with a single class of heterocycles has its own theoretical methods section. The “Experimental Structural Methods” section has received a strong impulse since, with some exceptions, the great majority of the reported derivatives have been adequately characterized. As already done in CHEC-II(1996), all six systems are discussed separately with each discussion following the same general format. In the case particular sections are not mentioned, it means that no chemistry has been reported.