Resolution of 3-methyl-3-phospholene 1-oxides by molecular complex formation with TADDOL derivatives

The antipodes of 1-phenyl-3-methyl-3-phospholene 1-oxide 1a were separated in good yield and in high enantiomeric excess (∼99% ee) by resolution via formation of diastereomeric complexes with (4R,5R)-(−)- and (4S,5S)-(+)-4,5-bis(diphenylhydroxymethyl)-2,2-dimethyldioxolane 2 (TADDOL) or (−)-(2R,3R)-α,α,α′,α′-tetraphenyl-1,4-dioxaspiro[4.5]decan-2,3-dimethanol 3. The method was also suitable for the resolution of the 1-ethoxy-3-phospholene derivative 1b, suggesting that our novel procedure may be of general value, both for the resolution of chiral phosphine oxides and phosphinates.

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(+)-(S)-1-Phenyl-3-methyl-3-phospholene 1-oxideC11H13OPEe = 99.0%[α]D25=+36.6 (c 1, CHCl3)

(+)-(S)-1-Phenyl-3-methyl-3-phospholene 1-oxide-(4S,5S)–(+)-4,5-bis(diphenylhydroxymethyl)-2,2-dimethyldioxolane complexC42H43O5PEe = 99%[α]D20=+56.0 (c 1, CHCl3)