Chemistry of sulfenic acids. 5. A novel rearrangement of 2,4,6-trineopentylbenzenesulfenic acid to 2-tert-butyl-4,6-dineopentylbenzo[b]thiete and 3,3-dimethyl-4,4-dihydro-6,8-dineopentylbenzo[b]thiopyran. Synthesis of thiete sulfoxides