Stereospecific cleavage of carbon‐phosphorus bonds: Stereochemical course of the phosphinoyl curtius (harger) reaction

Abstract

The homochiral phosphinic azides (R,R)-1 and (S,S)-1 were prepared in enantiomerically pure form by resolution of diastereomeric phosphinamides derived from (S)-l-phenylethylamine and (R)-phenylglycine. Irradiation of the azides in methanol induced a photo-Curtius rearrangement to phosphonamidates in which the stereogenic carbon unit migrated to a nitrogen atom. Hydrolysis of the phosphonamidates produced 1-phenylethylamine, which was 99.0% e.e. and of the same configuration as the carbon unit in the starting azide (99.0% retention).

N,P,P-Triisopropylphosphinic amide

“…For a similar synthesis of the title compound, see: Brü ck et al (1995). For similar structures of R 2 P(O)NHR in which the P atom has at least one attached alkyl substituent, see: Burns et al (1997); Denmark & Dorow (2002); Kolodiazhnyi et al (2003); Francesco et al (2010). 115 parameters H-atom parameters constrained Á max = 0.39 e Å À3 Á min = À0.16 e Å À3 Table 1 Hydrogen-bond geometry (Å , ).…”

“…Aminophosphines with alkyl-substituents undergo oxidation very easily compared to their analogue aryl-substituted species. Most of the structurally characterized P,P-diorganylphosphinic amides R 1 R 2 P(O)NHR 3 have a sterogenic phosphorus or nitrogen centre (Burns et al, 1997, Denmark et al, 2002, Kolodiazhnyi et al, 2003and Francesco et al, 2010). Here we report about the structural characterization of the known compound ( i Pr) 2 P(O)N(H) i Pr (Fig.…”

Tetramethylguanidinium Azide (TMGA) - A Versatile Azidation Agent

“…3,4 TMGA is frequently used as a source of azide, in nucleophilic addition, substitution, azidolysis of epoxides, and heterocyclic ring formation. 5 It has been successfully used for the synthesis of alkyl, 2 alkenyl, 6 propargyl, 7 heteroaryl, 8 acyl, 9 phosphinic, 10 and sulfonyl azides 11 as well as for the preparation of tert-butyl azidoformate, 12 tetrazoles, 13 b-azido alcohols, 14 a-azido ketones 15 and a-amino acid derivatives. 16…”