7284-49-3Relevant academic research and scientific papers
New highly diastereoselective synthesis of phosphoramidates. A route to chiral methyl p-nitrophenyl alkylphosphonates
Cavalier, Jean-Fran?ois,Fotiadu, Frédéric,Verger, Robert,Buono, Gérard
, p. 73 - 75 (1998)
A new, efficient and highly enantioselective synthesis of methyl p-nitrophenyl alkylphosphonates 4a-c is described. Alkylphosphonic dichloride 1a-d reacted successively with L-proline ethyl ester and p-nitrophenol to afford phosphoramidates 3a-d in 97% de. Boron trifluoride catalysed methanolysis gave 4a-c with 93% ee. Absolute configurations of compounds 4c and 3c were established by correlation with the X-ray structure of HPL-colipase-(-)-4c complex. 31P NMR studies indicates that monochloro phosphoramidates (Rp)-and (Sp)-2c undergo fast epimerisation. The observed diastereoselectivity in favour of (Sp)-3c results from a faster reaction of (Rp)-2c as compared to its epimer, according to the Curtin-Hammett principle.
1,8-Diazabicyclo[5.4.0]undecene mediated transesterification of p-nitrophenyl phosphonates: A novel route to phosphono esters
Tawfik,Eshhar,Bentolila,Green
, p. 968 - 972 (2007/10/02)
DBU (1,8-diazabicyclo[5.4.0]undecene) was found to efficiently mediate the transesterification of p-nitrophenyl (PNP) phosphonates by various alcohols. The reactions of bis-PNP phosphonates in the presence of DBU, using both primary and secondary alcohols, phenols and amines, proceed rapidly and with high yield to afford the corresponding monoalkyl/aryl mono-PNP phosphonates as sole products (1, Scheme 2). The resulting monoalkyl/aryl mono-PNP phosphonates can be further reacted with a second alcohol to give the corresponding differently disubstituted phosphonates 3, or selectively hydrolysed to yield the monoalkyl/aryl phosphonic acids 2. We have applied this chemistry to the preparation of a series of phosphono ester transition state analogues 11a-e (Scheme 3) that were used as haptens for raising catalytic antibodies.
