Alkylations of 1,2-alternate Calixarene
Rodriguez, Abelardo H.
A 1,2-altemate calixarene conformer (25,26-dibenzoyloxy-27,28-dihydroxy calixarene) was synthesized from the more common 1,3-dibenzoyloxy flattened cone conformer. The 1,2-altemate conformer was exhaustively alkylated with methyl, ethyl, and «-propyl tosylate. The 1,2-altemate conformation was conserved during méthylation while in the ethylation and propylation, the products were a 1,3-altemate 1,3-diester and a partial cone 1,3-diester. The 1,2 alternate calixarene was also alkylated in a stepwise fashion to find the pathway for the exhaustive alkylation process. Methyl and «-propyl tosylate were used as the alkylating agents in the first alkylation of the 1,2-altemate conformer. The 1,2-altemate diester stereochemistry was retained with the methyl tosylate, however, in the case of the «-propyl tosylate, the reaction yielded 1,2-dibenzoyloxy calixarene in cone and partial cone conformations. The second méthylation stayed in the 1,2-altemate 1,2-diester orientation, as in the exhaustive alkylation. Likewise, the second propylation yielded the same 1,3-altemate diester and 1,3-diester partial cone conformations as did in the exhaustive alkylations. It was determined that size of the electrophile determines whether migration of the ester will happen. In the case of the methyl tosylate, no migration occurred, where as in the case of the ethyl and «-propyl tosylate, migration did occur. However, in the alkylation of ethyl and propyl, the 1,2-diester orientation was preserved after the first alkylation, but during the second alkylation, there was a migration of the 1,2-diester to the 1,3-diester.
Rodriguez, A. H. (2002). Alkylations of 1,2-alternate Calixarene (Unpublished thesis). Southwest Texas State University, San Marcos, Texas.