- Kinetics and mechanism of the benzylaminolysis of O,O-diethyl S-aryl phosphorothioates in dimethyl sulfoxide
-
The reactions of O,O-diethyl Z-S-aryl phosphorothioates with X-benzylamines are kinetically investigated in dimethyl sulfoxide at 85.0 °C. The Hammett (log k2 vs δX) and Broensted [log k2 vs pKa(X)] plots are biphasic concave downwards for substituent X v
- Adhikary, Keshab Kumar,Lee, Hai Whang
-
scheme or table
p. 3587 - 3591
(2012/01/11)
-
- Transformation of Arylmethylamines into α-Aminophosphonic Acids via Metalated Phosphoramidates: Rearrangement of Partly Configurationally Stable N-Phosphorylated α-Aminocarbanions
-
N-Benzyl phosphoramidate was protected at nitrogen with a TMS, p-toluenesulfonyl, Boc, lithium carboxylate, or diethoxyphosphinyl group and metalated with s-BuLi or LDA at -78 °C at the benzylic carbon. For the latter three protecting groups, the intermediate α-amino(phenylmethyl)-lithiums isomerized to N-protected α-aminophosphonates (phosphoramidate-aminophosphonate rearrangement). (R)-N-[1-2H1]Phenylmethyl phosphoramidate in combination with Boc or (EtO)2P-(O) was used to demonstrate that metalation occurs with a high primary kinetic isotope effect (kH/kD 13-50) and migration of the diethoxyphosphinyl group with retention of configuration at carbon. Furthermore, the short-lived carbanion lithium pairs are partly configurationally stable as the aminophosphonates formed with the two protecting groups have enantiomeric excesses of 79 and 24%, respectively. When homochiral lithium amides derived from (R)-N-isopropyl-1-phenylethylamine and (R,R)-N,N-di(1-phenylethyl)amine were used to induce a phosphoramidate-aminophosphonate rearrangement, chiral nonracemic α-aminophosphonates were formed (ee 26-35%). Three racemic aminophosphonates were deprotected with hot 6 M HCl and purified by ion-exchange chromatography on Dowex 50W,H+ to exemplify the transformation of phenyl-, p-tolyl-, and (1′-naphthyl)methylamine into aminophosphonic acids via lithiated phosphoramidates.
- Hammerschmidt, Friedrich,Hanbauer, Martin
-
p. 6121 - 6131
(2007/10/03)
-
- N-(diethoxyphosphoryl)aldimines as synthetic equivalents of A1 type synthons
-
Novel organophosphorus reagents useful for convergent synthesis of primary amines are presented.
- Zwierzak, Andrzej,Napieraj, Anna
-
-