Cyclopropyl carbinol, rearrangements with

These electrophilic conjunctive reagents require donor reactants. The cyclopropyl-carbinols as precursors to cyclobutanones arise by simple addition of organometallics. For example, the cyclobutanone 47 derives by addition of vinyllithium to 44 followed by rearrangement with aqueous fluoroboric acid 92). In some cases, this route to cyclopropylcarbinols is preferred. Addition of 41 to aldehydes or ketones... 

Julia and co-workers (87, 88) have developed a novel synthesis of homoallyl-ic bromides by rearrangement of cyclopropyl carbinols on treatment with hydrobromic acid. For instance, the secondary cyclopropyl carbinols 301 have been converted into trans-bromo olefins 302 with 90-95% stereoselectivity. 

Due to the higher oxidation level cyclopropylcarbinyl-homoallyl rearrangement (see also Section IV.C) of oxycyclopropanes gives, y-unsaturated carbonyl compounds. This feature has been discovered by Julia and coworkers, who reacted certain esters with Grignard reagents or LiAlH4. The corresponding cyclopropyl carbinol opens under acidic conditions to j5,y-unsaturated aldehydes (equation This conversion also works for... 

Ph3Si ethylene oxide catalytically adds PhSH to give a- and -adducts in 6 1 ratio, and serves as a vinyl dication equivalent with RCu to give alkenes stereoselectively, while epoxides rearrange in the presence of silylated nucleophiles Diphenylmethylsilylation of cyclopropane carboxylates gives the C-silylated ester which then form C-silylated cyclopropyl ketones, P-silyl cyclopropyl carbinols, and alkylidene cyclopropancs, which ring expand to the... 

Under similar conditions, the title compound is either used directly or presumed to be formed in situ from PdCl2 and CuBr2 to catalyze the rearrangement of 2-(arylmethylene)cyclopropyl-carbinols to afford (arylcyclobutenyl)carbinols with good to excellent regioisomeric ratios (eq 11). ... 

As reported by Ranu et al., cyclopropyl carbinols with aryl substituents were found to rearrange to butadienes with catalytic In(OTf)3 either at room temperature or acceleration through sonication [298] (Figure 8.138). 

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