Cyclobutyl methanesulfonate

Cyclobutyl 4-methylbenzenesulfonate, 3404 Cyclobutylmethyl methanesulfonate, 2510 Cyclopentylmethyl methanesulfonate, 2867 1-Pentyl methanesulfonate, 2550 See also sulfur esters... 

However, the ring expansion of 1-substituted tertiary cyclopropanemethanols to tertiary fluo-rocyclobutanes is efficiently brought about with pyridinium poly(hydrogenfluoride) in the presence of diisopropylamine and potassium fluoride-hydrogen fluoride.19 2(1 Under the strictly anhydrous conditions employed, the intermediate cyclobutyl cation is efficiently trapped. Illustrative is the rearrangement of methanesulfonate 9, the key step in a synthesis of ( )-2-fluorograndisol.21 Other examples are collected in Table 3. 

Cyclobutyl 4-methylbenzenesulfonate, 3398a Cyclobutylmethyl methanesulfonate, 2510 c/.v-Cyclododecene, 3345 f Cycloheptane, 2845 f 1,3,5-Cycloheptatriene, 2786 f Cycloheptene, 2833 f 1,3-Cyclohexadiene, 2354 f 1,4-Cyclohexadiene, 2355... 

It is relevant to discuss briefly at this point the stereochemistry and mechanism of the cyclopropylcarbinyl-cyclobutyl-homoallyl rearrangements. Solvolysis of cyclopropylcarbinyl, cyclobutyl, and homoallyl derivatives bearing stereospecific labels or substituents lead to rearranged products in which the stereochemical relationships in the starting material are retained (74—76). The stereochemistry is illustrated below with the hydrolysis of specifically deuterated cyclopropylcarbinyl methanesulfonate... 

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