Thiocarbonyl compounds in 4 2 cycloaddition

Most aspects of the reactivity of thiocarbonyl compounds in the Diels-Alder reaction, either as dienophiles or as heterodienes (see Section 

are discussed in books [483, 519, 520] and reviews [120, 521] we have previously noted (see Section 2.8.1) the trapping of thioaldehydes through their dihydrothiopyran adducts. 

These adducts easily undergo cycloreversion reactive unstable thioaldehydes can thus be conveniently stored and recovered, and their chemistry has been greatly developed over the last 10 years, mainly by Vedejs and Kirby [126, 253], Vedejs elegantly used the thiopyranic heterocycles, via a [2,3] sigmatropic shift of a sulfur ylide [508], as precursors for medium sulfide rings, applied to the synthesis of complex natural products in the cytochalasin-zygosporin family [522, 523] for instance. 

Although almost all kinds of thiocarbonyl compounds are good dienophiles, synthetic applications derived from the Diels-Alder adducts of thioketones, thionesters and dithioesters remain rather rare and focused on specific targets, as in the preparation of a fragment of the antibiotic erythronolide from the cycloadduct formed regioselectively from 2-methyl-1.3-pentadiene and an a-oxodithioester, a particularly efficient dienophile [524]. 

---