Chelation Controlled Intermolecular Hydroacylation: The Direct Addition of Alkyl Aldehydes to Functionalised Alkenes.

General Information. Commercial reagents were purified prior to use following the guidelines of Perrin and Armarego.1 Unless otherwise specified, all reactions were performed in anhydrous conditions under a nitrogen atmosphere. All solvents were freshly distilled from sodium (diethyl ether, toluene and tetrahydrofuran) or calcium hydride (acetonitrile, dichloromethane, 1,2-dichloroethane and dimethyl sulfoxide) and stored over molecular sieves under nitrogen or argon. All reactions involving rhodium complexes were performed using standard Schlenk line techniques under argon; substrates for hydroacylation experiments were purified by distillation or recrystallisation before use. The rhodium pre-catalyst complexes were stored in sealed, argon-filled Schlenk tubes in a refrigerator, but they are relatively moisture- and air-stable, so could be weighed on a bench-top balance. NMR analyses were carried out on Bruker 300AM or Varian 400 instruments. 1H and 13C chemical shifts d are quoted in parts per million, relative to tetramethylsilane. Multiplicities of the signals are recorded as follows: s = singlet, br = broad signal, d = doublet, t = triplet, q = quartet, quint. = quintet and m = unresolved multiplet. Coupling constants J are quoted in Hertz. Infrared measurements were made as a liquid film in the range 4000–600 cm-1, using a Perkin-Elmer FT-1000 spectrometer; only significant peaks are quoted. The following abbreviations are used: br = broad, w = weak. Mass spectrometry measurements were performed at the EPSRC National Mass Spectrometry Service Centre, University of Wales Swansea; values are quoted as m/z with relative intensity in parentheses