THE CHEMISTRY OF TRANS-BICYCLO(N.1.0)ALKANES

The diol-monotosylate rearrangement was utilized to synthesize the highly strained compounds, trans-bicyclo{4.1.0}heptan-2-one and trans-bicyclo{4.1.0}heptan-2-ol. The bicyclo{4.1.0}heptanes and bicyclo{3.2.0}heptanes prepared in the synthetic sequence were fully characterized and all ('13)C assignments made, using carbon-hydrogen coupling constant values and calculated chemical shifts. The corresponding cis-bicyclo{4.1.0}heptanes, cis-bicyclo{4.1.0}heptan-2-one, cis-bicyclo{4.1.0}heptan-cis-2-ol and cis-bicyclo{4.1.0}heptan-trans-2-ol, were also synthesized and fully characterized.;The reaction of trans-bicyclo{4.1.0}heptan-2-ol with acid was studied. A very unusual cleavage of the C(,1)-C(,2) bond resulted in the formation of 4-cyclopropylbutanal as a product of the reaction. Deuterium incorporation studies revealed that deuterium was introduced trans to the alkyl side chain in 4-cyclopropylbutanal indicating that attack of deuterium at C(,1) takes place with retention of configuration. On the basis of the stereochemistry of deuterium incorporation in 4-cyclopropylbutanal, the stereochemistry of the hydroxy group in trans-bicyclo{4.l.0}heptan-2-ol was assigned as endo. A cyclopropylcarbinylcyclobutyl cation interconversion mechanism or a biradical type mechanism was proposed for the formation of cis-bicyclo{4.1.0}heptan-cis- and trans-2-ol as reaction products.;trans-Bicyclo{4.1.0}heptan-2-ol was found to react readily with pyridiuium bromide perbromide to give one product, 6-bromo-8-oxabicyclo{3.2.1}octane. The reaction of trans-bicyclo{4.1.0}heptan-2-one with acid was also studied and cis-bicyclo{4.1.0}heptan-2-one was identified as the major product of the reaction.;Approximate molecular orbital methods were used to investigate the nature of bonding in trans-bicyclo{n.1.0}alkanes. Energy-minimized geometries were obtained for trans- and cis-bicyclo{4.1.0}heptane and trans- and cis-bicyclo{3.1.0}hexane. Hybridizations and coupling constants were also calculated. Some of the calculations were correlated with experimental observations. The unusual carbon-hydrogen coupling constants observed for the bridgehead positions in trans-bicyclo{4.1.0}heptanes were rationalized.;A novel rearrangement reaction induced by nucleophilic attack of carbonyl oxygen on silicon was discovered. The new rearrangement was used to synthesize 1-trimethylsilyloxy-cis-bicyclo{3.2.0}heptan-7-one, a key intermediate in the synthetic pathway to trans-bicyclo{4.1.0}alkanes, by a shorter route. The rearrangement has much potential synthetic utility.