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Issue 4, 2002
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Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 17.1 Preparation of aliphatic amino acid derived γ-alkoxycarbonylamino-β-oxo ylides and pyrolysis to give α,β-acetylenic γ-amino acid and GABA analogues

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Abstract

A series of eleven α-aminoacyl stabilised phosphorus ylides 9–19 have been prepared by condensation of N-alkoxycarbonyl protected amino acids with Ph3P[double bond, length as m-dash]CHCO2Et using a carbodiimide peptide coupling reagent. Upon flash vacuum pyrolysis at 600 °C, these undergo extrusion of Ph3PO to give the corresponding α,β-acetylenic γ-amino esters 21–29, 33 and 34 in moderate yield. In two cases the terminal alkynes 30 and 31 are also formed. The β-aminoacyl ylide 20 from β-alanine similarly gives the α,β-acetylenic δ-amino ester 35 upon pyrolysis. Regioselective addition of HBr to the triple bond of one acetylenic ester 25 was observed giving a mixture of E and Z α-bromoacrylates 36. Hydrogenation of the N-Cbz acetylenic esters 21–23 and 33 results in N-deprotection and hydrogenation of the triple bond to afford the chiral GABA analogues 37–40 in 70 –>95% ee as determined by 19F NMR of their Mosher amides. Fully assigned 13C NMR spectra of all the ylides and acetylenic ester derivatives are presented.

Graphical abstract: Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 17.1 Preparation of aliphatic amino acid derived γ-alkoxycarbonylamino-β-oxo ylides and pyrolysis to give α,β-acetylenic γ-amino acid and GABA analogues

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Article information


Submitted
12 Nov 2001
Accepted
19 Dec 2001
First published
21 Jan 2002

J. Chem. Soc., Perkin Trans. 1, 2002, 533-541
Article type
Paper

Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 17. Preparation of aliphatic amino acid derived γ-alkoxycarbonylamino-β-oxo ylides and pyrolysis to give α,β-acetylenic γ-amino acid and GABA analogues

R. A. Aitken, N. Karodia, T. Massil and R. J. Young, J. Chem. Soc., Perkin Trans. 1, 2002, 533
DOI: 10.1039/B110243E

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