Adamantanethione .S -oxide

High-level quantum-chemical calculations on the 3 + 2-cycloadditions of thioformaldehyde 5 -imides, S -methylide, S-oxide, and 5-sulfide have been reviewed. Theoretical studies on the 1,3-dipolar cycloaddition between thioketene 5-oxide and methyleneimine show that this reaction is concerted but non-synchronous. Adamantanethione 5-methylide reacts with thiocarbonyl compounds to produce 1,3-dithiolanes. A density-functional-theory study of the cycloaddition of the sulfine H2CSO predicts the 2 + 3-mechanism having the lowest pathway, with an activation barrier of 12.3kcalmoP. R The thermal and photochemical reactions of fluorenethione 5-oxide (69) with cyclooctyne (70) involves an initial 1,3-dipolar cycloaddition to produce the adduct (71), followed by an efficient sulfur transfer to cyclooctyne to produce the enone (72) and the dithiin (73) (Scheme 26). ° ... 

Hetero Diels-Alder reactions of 3,4-di-fcrf-butyIthiophene 1-oxide with thioaldehydes and thioketones take place exclusively at the syn-jt-face with respect to the S=0 bond, like the Diels-Alder reactions with ketones. Thiophosgene and adamantanethione can also react with 3,4-di-(erf-butylthiophene 1-oxide to afford the corresponding syn-tr-face products (Scheme 44) [49]. 

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