Photochemical induced 1.2- hydrogen migration

The following types of thiopyran isomerizations have been reported in the last decade valence-bond tautomerism, endocyclic hydrogen shifts and migration of nonhydrogen substituents. Thermal processes will be mentioned here and photochemically induced isomerizations will be discussed in Section V,I. 

Essential to the identification of H-induced defects in silicon was the use of a remote hydrogen plasma system as described in Section 1.2. The alternative of direct immersion in a plasma introduces charged-particle bombardment and possible photochemical effects that can obscure the purely chemical consequences of hydrogen migrating into silicon. While the evidence presented below strongly argues for the existence of H-induced defects, many issues remain to be resolved. 

The photochemical light-induced reaction of 9-boradecalin (2) with bromine in the presence of water yields 6-hydroxy-6-boraspiro[4.5]decane (16). The structure (16) was confirmed by oxidation with alkaline hydrogen peroxide, which gave l-(4-hydroxybutyl)cyclopentanol (17) (Scheme 4) <74JOC861>. It is evident that the radical a-bromination occurs selectively at the a-tertiary hydrogen atom, rather than at the a-secondary position. Under the action of water, the intermediate a-bromoborane (18) undergoes a rapid and facile migration of the C—B bond from boron to a-carbon, and the new C—C bond is formed (Scheme 4). 

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