The synthesis of Nπ-alkylhistamines

Abstract
The use of the phthaloyl and pivaloyloxymethyl protecting groups in a new synthesis of Nπ-alkylhistamines is described. The Nα-phthaloyl-Nτ-pivaloyloxymethyl-protected derivative of histamine was obtained by selective alkylation of Nα-phthaloylhistamine with chloromethyl pivalate. Quaternisation at the Nπ-nitrogen atom with either mtethyl iodide or benzyl bromide followed by removal of the protecting groups, either simultaneously or sequentially, furnished the required Nπ methyl- and Nπ-benzyl-histamines.