Anions cyclopropabenzenyl

An ab initio study of the effect of a-substituents on the acidity of cyclopropaben-zene has shown that a-substituents stabilize the cyclopropabenzenyl anion (5) less efficiently than the cyclopropenyl anion (6).2 The attachment of induedvely/field acting substituents attached to the carbanionic site predominantly stabilize the cyclopropenyl anion by increasing the, v character of the lone pair, diminishing the antiaromatic character of the three-membered ring at the same time. 

An overview on cycloproparenyl anions has also been reported.3 According to theoretical calculation, cyclopropabenzenyl anion is by ca 145 kJmol-1 more stable than the parent cyclopropenyl anion. It has been shown that the stability of the cyclopropabenzenyl anion could be considerably enhanced by substitution of the aromatic ring with fluorine and cyano groups, and also by a linear extension of the aromatic backbone. 

Silylation of the cyclopropabenzenyl anion (6) with chlorotriisopropylsilane and a repetition of the sequence provides a sterically demanding disilyl which is nitrated " (67% HNO3) at C(3) to give 113 in 58% the use of ultrasound in the nitration improves the yield of product Attack of the electrophile at 3) of 1 is clearly in accord with the location of the A range of transformations of the nitro functionality is possible as illus-... 

Peterson olefination involving cyclopropabenzenyl and cyclopropa[Z ]naphthalenyl anion intervention, respectively. Particularly noteworthy is the fact that subjection of disilyl-containing chromium(O) complexes (104, or its anthracene analogue) to r-BuOK provides C(i) anion without the loss of chromium in the case of 104 Peterson olefination has provided the corresponding complexed alkylidene derivative in high yield (equation 25) ", but the compound is unstable and decomposes upon attempted purification. 

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