.alpha.-Halo sulfones. XXI. Bishomoconjugative rearrangement pathway. Structural bond relocation attending the dehydrohalogenation of unsaturated cyclic .alpha.-halo ketones and sulfones

Abstract

Reaction of 7-bromo-c/s-bicyclo[4.3.0]nona-2,4-dien-8-one (la) as well as its 1,6-dimethyl (lb) and 1,6tetramethylene derivatives (2) with potassium /erf-butoxide in dimethyl sulfoxide for short periods of time at 25°r esults in dehydrobromination with structural bond reorganization to give bicyclo[4.2.1 ]nona-2,4,7-trien-9-ones (19, 21, and 26). Direct irradiation of these bridged ketones causes decarbonylation and cyclooctatetraenes are produced. When these molecules experience triplet sensitization, photoisomerization to barbaralones operates. 7-Chloro-8-thiabicyclo[4.3.0]nona-2,4-diene 8,8-dioxides rearrange in analogous fashion when treated with strong base in a polar aprotic solvent. The resulting bridged sulfones (34, 38, and 43) can be made to extrude sulfur dioxide by thermal or photochemical methods. These striking and unprecedented reactions provide a useful

Cheletropic Reactions

“…However, as minor primary coproducts l,ir0AW-3,5-hexatriene and an isomeric hydrocarbon (not 1,3cyclohexadiene) were also detected. Photoextrusions analogous to that of 10 have been reported (Paquette et al, 1973). The bridged dihydrothiepin dioxide (10) was submitted to irradiation under approximately the same conditions as was 6.…”

The question of delocalization in "anchored" ions with potential trishomoaromatic character. 1. Reduction of tricyclo[5.4.1.04,12]dodeca-2,5,8,10-tetraene as a route to the 10.pi.11C dianion

“…The mixture was placed atop a 16 X 2 cm slurry packed 30% AgNOs-silica gel chromatography column. Elution with petroleum ether (30-60 °C) and petroleum ether-ether mixtures furnished 1.6 g of pure 16. Elution with increasing amounts of methanol in ethyl ether yielded 450 mg of 23 contaminated with small amounts of 14.…”

“…Thermolysis of endo-Tricyclo[4.2.2.02'5]dodeca-3,7,9,l 1-tetraene (16). Hydrocarbon 16 (30 mg) was sublimed into the same hot tube apparatus at 560 °C and 1 mm with a slow stream of nitrogen.…”

“…Acetone-Sensitized Photoisomerization of enrfo-Tricyclo-[4.4.2.02-5]dodeca-3,7,9,l 1-tetraene (16). A sample of 16 (10 mg) was dissolved in 4 ml., of acetone and placed in a Pyrex test tube.…”

Sulfur-Containing Carbanions

“…A novel "bishomoconjugative" analog of the Ramberg-Bäcklund reaction has been reported (Eq. 2-67; Paquette et al, 1973).…”