Azulenones

The bicyclic oxepin 8//-3-oxacyclohept[d]oxepin-8-one dissolved in trifluoroacetic acid undergoes a rearrangement to the expected phenol derivative 1. Substituents in the 2- and/or 7-position of the oxepin part, however, give rise to the formation of l-acylazulen-6-ols 2 by ring contraction.148 The 2,7-diphenyl derivative affords a mixture of l-benzoyl-2-phenylazulen-6-ol (37%), l-benzoyl-2-phenylazulen-6(l//)-one (35%), and 2-phenylazulen-6-ol (23%), which was presumably formed via the azulenone and a shift of the benzoyl substituent to the oxygen. 

Et3N, the adduct (126) yielded azulenone (127). The ketone (127) reacted with Wittig reagent to afford a [3.3 1] mixture of 1-epi-P-bulnesene (128a) and P-bulnesene (128b)A1 ... 

Diazoketone Cyclization onto a Benzene Ring 3,4-Dihydro-l(2H)-Azulenone... 

DIAZO KETONE CYCLIZATION ONTO A BENZENE RING 3,4-DIHYDRO-1(2H)-AZULENONE (1(2H)-Azulenone, 3,4-dlhydro-)... 

A nucleophilic attack of hydrazine occurs at the 5-position of the aza-azulenone 15, followed by ring opening and formation of A2-pyrazoline 49 (70JCS(C)1490) (Scheme 5). 

Flash vacuum pyrolysis of the enamine (86.4) gave a low yield of the 4-aza-azulenone. The chemistry of 4-aza-azulenes has been reviewed [3503]. 

A similar strategy starts with an intramolecular alkyne insertion of an a-diazo ketone. Thus, rhodium(II)-catalyzed reaction of 2-(6,8-nonadien-1-ynyl)-or-diazoacetophenones 112 at 0°C in dichloromethanc affords cyclopen%]azulenones 115 in 50-58% yield879. Due to the enhanced solubility, rhodium(II) mandelate has proved to be superior to the acetate. 

R,4R,7R SuS)-octuhydro-4-hydroxy-7-isopropent7-/,4-dimethyl-2(IH)-azulenone yield 90%... 

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