Neopentyl tosylate, solvolysis

As far back as 1960 Winstein and L. de Vries noted a high anchimeric acceleration (10 °) in the solvolysis of pentamethylcyclopentadienylcarbinol tosylate 484 as compared with neopentyl tosylate chosen as a model convenient for comparison. The kinetically controllable products in this reaction were olefine 485 and... 

Worthy of note is also the point of view of Traylor et al. on the mechanism of solvolysis of neopentyl-type systems. In their opinion the higher rate of reaction in the case of 2,2,3,3-tetramethylbutyl tosylate in comparison with neopentyl tosylate can be accounted for (at least partially) by the vertical stabilization of the developing carbonium centre by the electrons of the C —bond ... 

Hydroxy-4,4-dimethyl steroids and triterpenes16 such as lanosterol possess a-substituted neopentyl systems which rearrange easily. The reagent of choice for this rearrangement on a preparative basis is phosphorus pentachloride. Mechanistic studies of the ring contraction have been carried out on C-3 acetates, mesylates and tosylates under solvolysis conditions.1... 

Any Sn1-Sn2 mechanistic complication should be absent in the solvolysis of a-t-butylbenzyl tosylates [15], which have a neopentyl-type structure (Tsuji et al., 1990). Indeed, the substituent effect in the solvolysis is accurately described by (2) with an r value of 1.09 which differs from the value r = 1.0 for the a-cumyl chlorides solvolysis. Based on the linearity of the correlation of the substituent effects on the solvolyses of [14] and [15] in 80% aqueous acetone, an Sn1-Sn2 mechanistic duality is also unlikely to be the cause of the exalted r value observed in the solvolysis of [14]. 

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