Preparation and dienone-phenol rearrangement of 3-heterospiro[5.5]undec-7,10-dien-9-ones

The 3-heterospiro[5.5]undec-7,10-dien-9-ones (C), which were prepared by dehydrogenation of the 3-heterospiro[5.5]undec-7-en-9-ones (A) with phenylselenenyl chloride under strong basic conditions using LDA [7], underwent a dienone-phenol rearrangement to yield the new benzo[d]heteroepan-7-oles (G) under strong acidic conditions [8].

a: PhSeCl, LDA/THF, -80 °C; b: H2O2; yield: 35 - 70% ;
c: X = N-CH3: 9N H2SO4, 10 d; yield: 40%; X = S: 6N H2SO4, 10 d; yield: 40%; X = O: 3N H2SO4, 10 d; yield: 40%