title: Rearrangement of lithiated S-alkyl O,O-dialkyl thiophosphates: scope and stereochemistry of the thiophosphate-mercaptophosphonate rearrangement.
abstract: S-Alkyl O,O-dialkyl thiophosphates are prepared by alkylation of the triethylammonium salt of O,O-diisopropyl thiophosphoric acid. S-Benzyl thiophosphate was metallated at temperatures of ≥-45 °C by trityllithium and LiTMP (lithium 2,2,6,6-tetramethylpiperidide) and S-alkyl thiophosphates only by LiTMP to give dipole-stabilised carbanions which rearrange to α-mercaptophosphonates in yields of up to 45%. Metallation occurs with a high primary kinetic isotope effect (k(H)/k(D) up to ≈50). When the lithium (R)-N-isopropyl-1-phenylethylamide was used to induce the isomerisation of S-pentyl thiophosphate an α-mercaptophosphonate with an ee of 22% was isolated. (R)-S-[1-D(1)]hexyl O,O-diisopropyl thiophosphate was rearranged to a dextrorotary α-mercapto-[1-D(1)]hexylphosphonate, whose (R)-configuration was determined by chemical correlation. The thiophosphate-mercaptophosphonate rearrangement proceeds with retention of configuration.
authors.affiliation: Institute of Organic Chemistry, University of Vienna, Währingerstrasse 38, A-1090, Wien, Austria.
authors.forename: Violeta
authors.initials: V
authors.lastname: Philippitsch
authors.forename: Friedrich
authors.initials: F
authors.lastname: Hammerschmidt
mesh_terms: D000478:Alkylation; D008094:Lithium / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D063065:Organophosphonates / Q000737:chemistry*; D010710:Phosphates / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D009942:Organometallic Compounds; D063065:Organophosphonates; D010710:Phosphates; D008094:Lithium; C035638:thiophosphoric acid