Crystal structure of a complex formed from triphenylphosphine oxide and 6-chloro-2-pyridone.

from Wittig-type reactions is a quite useful tool in synthetic organic chemistry, provided that an olefinic product is easily isolable.1 During our exploration of coupling reactions between phthalimide and phosphorane to prepare bioactive phthalimidine derivatives, the inevitably-formed triphenylphosphine oxide was found to mingle with the expected product, making the isolation difficult. Recently, we have reported hydrogen bonding-based molecular recognition of phenol derivatives by pyridones (=lactam moieties) which are similar to nucleic acid bases.2,3 These results encouraged us to investigate the complexation of “waste” phosphine oxide by means of some intermolecular interaction in order to find its potential utility. We describe here the crystal structure of a complex 1 formed from triphenylphosphine oxide and 6-chloro-2-pyridone. Equimolar amounts of triphenylphosphine oxide and 6-chloro2-pyridone were placed in a mortar and ground with a pestle to 1407 ANALYTICAL SCIENCES DECEMBER 2002, VOL. 18 2002 © The Japan Society for Analytical Chemistry