REACTIONS OF (2,4,6-TRI-T-BUTYL)THIOBENZALDEHYDE WITH DIAZO-COMPOUNDS- SYNTHESIS AND REACTIONS OF STERICALLY CONGESTED THIIRANES

Sterically congested thiiranes having a 2,4,6-tri-t-butylphenyl group were synthesized by the reactions of (2,4,6-tri-t-butyl)thiobenzaldehy de with sterically hindered diazo compounds. Thermal desulfurization o f the most congested thiirane, 2,2-di-t-butyl-3-(2,4,6-tri-t-butylphen yl)thiirane (15c), did not proceed even upon using highly reactive rea gents, such as hexamethylphosphorous triamide or organolithiums. The p hotoreaction of 15c did not give the corresponding styrene, but afford ed several products containing 2,4,6-tri-t-butylbenzo[b]thiophene and Dewar benzenes, l-3-(3,4,6-tri-t-butylbicyclo[2.2.0]hexa-2,5-dien- 2-y l)thiirane and t-butylbicyclo[2.2.0]hexa-2,5-diene-2-yl)-1-butene (24) , the latter of which is the first example for a vinyl-substituted Dew ar benzene. Compound 24 has a unique reactivity, giving a rearrangemen t product, t-butylbicyclo[2.2.0]hexa-2,5-diene-2-yl)-1-butene on therm olysis.