Spiro-bicyclo octane derivatives

Frejd and co-workers used a ring-closing metathesis strategy as the key transformation in their synthesis of several novel spiro-cyclohexene bicyclo[2.2.2]octane derivatives. Spiro-cyclohexene bicyclo[2.2.2]octane derivatives are rare molecular frameworks, with only a few examples reported to date. Olefin metathesis of diastereomeric homoallylic alcohols 200 and 202 using 10 mol % of 3 in refluxing dichloromethane provided the corresponding spirocyclic carbocycles 201 and 203 in 84 and 85% yields, respectively. 

The structures of a number of compounds containing four-membered rings have been determined by X-ray or electron diffraction methods. The crystal structures of 1-aminocyclobutanecarboxylic acid hydrochloride, the bicyclo[4,2,0]octane derivatives, (7) and (8), and of [4,4,2]propella-3,8-diene-ll,12-dione (9) have been determined by X-ray diffraction. The structure of l,2,3,3-tetrachloro-4,5-dimethyl-spiro-2,3-hexa-1,4-diene (10) in the gas phase has been determined by electron diffraction. Other structures determined by these methods are cited in the body of the text. 

With bridgehead substituted bicyclo[4,2.0]alkanes, each pair of cis- or /ran.v-fused systems gives essentially the same ratio of products. Thus, solvolysis of cis- and m 5-l-(3,5-dinitrophenyl-methoxy)bicyclo[4.2.0]octane in 80% aqueous acetone buffered with 2,6-lutidine at 140°C and 100°C, respectively, gave the same mixture of spiro[2.5]octan-4-ol 14 and bicyclo[4.2.0]octan-l-ol 13 obtained from spirocyclopropylmethyl cation derivatives, suggesting one or more common intermediates. ... 

The reaction of bicyclo[4.1.0]heptane with diborane and subsequent treatment with hydrogen peroxide produced predominantly cyclohexylmethanol (5b) in high yield.Under modified experimental conditions small amounts of isomeric methylcyclohexanol (6b) and cycloheptanol (7b) were isolated. In contrast to the hydroboration of alkenes, the cyclopropane cleavage reaction is inhibited by ethereal solvents such as diethyl ether, tetrahydrofuran or 2-methoxy-ethyl ether. Bicyclo[3.1.0]hexane reacted with diborane in a similar fashion to give mainly cyclopentylmethanol (5a).The reaction of l-methylbicyclo[4.1.0]heptane gave a mixture of cis- and tram-(2-methylcyclohexyl)methanol (5c) in an initial ratio of 60 40. Spiro[2.5]octane reacted with diborane to yield only products derived from scission at the spiro carbon. The main product was 2-cyclohexylethanol (8). ... 

Singh and co-workers applied their methodology for the synthesis of embellished spiro-fused bicyclo[2.2.2]octane systems to the synthesis of seven-membered ring carbocyclic derivatives. Treatment of diene 299 with 10 mol % of 3 in dichloromethane gave the corresponding spirocyclic carbocycle 300 in 86% yield. 

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