ABSTRACT
I. The current monograph presents systematic studies on thermal and catalytic rearrangements of chloroallyl aryl and bisaryl allyl esters. The interrelation between the allyl unit structure of the initial ester, composition and structure of transformation products is determined:
the origin of P.substituent in the allyl unit of allyl aryl ester causes no effect on thermal rearrangement mechanism, which is always conducted with inversion of the allyl unit in the initial ester. In the presence of catalyst, which is boron trifluoride etherate, the origin of p.substituent begins influencing on the rearrangement mechanism. Free electron pairs at atoms in P.methyl substituent stabilize allyl intermediate formed due to 0-C-bond hydrolysis. This promotes formation of rearrangement products with preservation of the ally I unit structure; thermal rearrangement of r-chloro-and P.dichloroallyl aryl esters is also conducted with the allyl unit inversion and provides for chromene formation. It shown for the first time that r-chloroallyl aryl ester in the presence of Bf)-O(C2H5)2 are rearranged to o-alkenyl-, o,o-dialkenyl phenols and o-alkenyl alkenyl aryl esters with preserved allyl unit structure of the initial ester, i.e. the reaction displays the intermolecular mechanism. The composition and structure of the rearrangement products of P,r-dichloroallyl aryl esters depends on temperature: chromenes are synthesized at 80°C, chromenes and o-alkenyl phenols with inversion and preserved structure of the allyl unit at 100°C; r.r-dichloro-and p,y,r-trichloroallyl esters are subject to thermal rearrangement and dissociation, whereas in the presence of BF J"O(C2Hs)2 they are rearranged without allyl unit inversion in the initial ester; thermal rearrangement of bisehters without substituents in the allyl unit results from the intramolecular reaction, stipulated by consecutive transformation of 0-C-bonds in the initial ester with participation of [3,3]-sigmatropic shift. Replacement of hydrogen atom in the r-position of allyl unit in the bisester by chlorine atom changes the rearrangement mechanism and forms unstable products without inversion of the allyl unit at the first stage. These products are then cyclized and subject to
intramolecularrearrangementbythesecondesterbondwithallylunit inversion.
