γ-Phosphono-γ-lactones. The use of allyl esters as easily removable phosphonate protecting groups

Abstract

During the synthesis of γ-lactones bearing a phosphonic acid group at the γ-position, difficulties were encountered generating the free phosphonic acids from corresponding esters. A protecting group used for carboxylic acids was adapted to phosphonic acids, making this transformation easy.

A Virtual Screening Hit Reveals New Possibilities for Developing Group III Metabotropic Glutamate Receptor Agonists

“…20 In the third strategy (method C, Scheme 3) the first P-C bond formation is similar to method B starting from aqueous hypophosphorous acid and protected vinylglycine or allylglycine to give the H-phosphinate derivatives 39 and 40 as previously described. 21 The second P-C bond formation is achieved by in situ generation of P III species by means of TMSCl or BSA 21 followed by a conjugate addition with a Michael acceptor (41,(44)(45)(46)(47)(48)(49)(50)(51)(52)56), a halide (42,43), or an aldehyde (53-55). Acidic hydrolysis and ion exchange chromatography purification afforded the desired amino acids [(S)-(þ)-1, 3, 4, 6, 7, 9-24; Scheme 3].…”

Synthesis and Selective N,O‐Functionalization of Pyrazolone‐Fused 3‐Aminoazepinones

“…allylglycine 5, [8] which was transformed into the corresponding amides 7 (Scheme 1). allylglycine 5, [8] which was transformed into the corresponding amides 7 (Scheme 1).…”

“…[a] Conversions based on HPLC analysis. allylglycine 5, [8] which was transformed into the corresponding amides 7 (Scheme 1). Reported procedures using 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC) as coupling agent gave very low conversions in our hands, [9] but the use of 1-[bis(dimethylamino)methylene]-1H-1,2,3triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate (HATU) gave access to amides 7a-d in good yields.…”

Convenient synthesis of bisphosphonomethylphosphoric acid

“…In order to preserve the phosphate-bisphosphonate structure the cleavage of the ester should be carried out under neutral conditions, which is usually done with allyl esters employing the Wilkinson catalyst chlorotris(triphenylphosphine)rhodium [11]. This catalyst has been successfully employed to obtain the expected bisphosphonomethyl-phosphoric acid in quantitative yield from its allyl ester.…”