Acetylene‐Substituted Phosphane Oxides: Building Blocks for Macrocycles

Phosphorus‐based macrocycles with acetylenic scaffolds have been built from acetylene‐substituted phosphane oxides that were formed from diisopropylphosphoramidic dibromide (3) and an acetylenic Grignard reagent. The four‐ and six‐edged macrocycles 15 and 16, in which the iPr2NP(O) units are connected through 1,3‐butadiyne rods, were obtained from the monosilylated derivative of iPr2NP(O)(C2H)2 (7) by multiple acetylene coupling reactions under oxidative Hay conditions. Reaction of iPr2NP(O)(Br)2 (3) with lithiated 1,2‐diethynylbenzene gave a mixture of cis and trans monocyclic bis(phosphane oxide) 18. An X‐ray crystal structure determination of the trans isomer shows the ring structure to adopt a puckered form.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)