Spectroscopic and Conformational Aspects

Spectroscopic and Conformational Aspects.—According to SCF (CNDO/2) theory, the u.v. spectrum of thiiran can be accounted for only if d-orbitals are included. Precise signal assignments and coupling constants are now 

Okazaki, K. Okawa, S. Wajiki, and N. Inamoto, Bull. Chem. Soc. Japan, 1971, 44, 3167. 

The reactions described above involve nucleophilic attack on a thiiran-ring carbon atom, but the cleavage of thiiran to give 1,6-dichloro-3,4-dithiahexane on treatment with 3-dichloroiodopyridine and the cleavage of thiiran derivatives by a-chloro-ethers to give 5 -(jS-chloro-alkyl)-monothioacetals almost certainly involve nucleophilic attack by chloride 

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