Photoisomerization of 5,5-dimethyl-3-(3,3-dimethylbut-1-nyl)-2-(pent-4-enyl)-cyclohex-2-enone to tert-butyl-(4,4-dimethyl-2-oxotricyclo[7.3.0.01,6] dodec-6-en-7-yl)carbene

Abstract

On irradiation (λ > 340 nm) cyclohexenone 1 is converted to a mixture of diastereoisomeric 4,4-dimethyl-7-(2,2-dimethylcyclopropyl)tricyclo[7.3.0.0 ^1,6]dodec-6-en-2-ones 2 via the title Carbene 4, which can also be efficiently trapped both by methanol or by oxygen to afford methyl ethers 5a and 5b or the pivaloyl derivative 6, respectively.