Highly Selective Electrophile‐Induced Cascade Reactions between <i>o</i>‐Alkynylbenzaldehydes and Styrene Oxides Leading to the Formation of 1‐Naphthyl Ketones

Abstract

Abstract An efficient method for the synthesis of naphthalene derivatives through reaction of o ‐alkynylbenzaldehydes and styrene oxides in the presence of molecular iodine was developed. The reaction involves Meinwald rearrangement of styrene oxides to form the corresponding aryl acetaldehydes. The enol forms of aryl acetaldehydes might undergo [4+2] benzannulation reactions with iodinated benzopyrilium ions, formed in situ from o ‐alkynylbenzaldehydes and iodine, to afford 1‐naphthyl ketones. The reaction was found to be highly selective, and of two possible products, only one was formed. Mechanistic aspects are discussed.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2009)