125942-78-1Relevant articles and documents
A New Direct Method for the Synthesis of Enantiomerically Pure Protected α-Amino Acids
Jackson, Richard F. W.,James, Keith,Wythes, Martin J.,Wood, Anthony
, p. 644 - 645 (1989)
The organozinc reagent (2), prepared from the protected β-iodo alanine derivative (3) using ultrasonic activation, is efficiently acylated using acid chlorides in the presence of (Ph3P)2PdCl2 to give high yields of enantiomerically pure protected γ-keto α
Synthesis of Enantiomerically Pure Unsaturated α-Amino Acids Using Serine-Derived Zinc/Copper Reagents
Dunn, Michael J.,Jackson, Richard F. W.,Pietruszka, Joerg,Turner, Debra
, p. 2210 - 2215 (2007/10/02)
Treatment of the serine-derived organozinc reagent 2, in benzene/dimethylacetamide, with a THF solution of CuCN*2LiCl gives rise to a zinc/copper reagent 6 which reacts directly with allylic halides and tosylates to give the corresponding enantiomerically pure substitution products 9 in 32-65percent yield (11 examples).The reaction proceeds by formal SN2' displacement of the leaving group.Reaction with propargyl halides gives the corresponding terminal allene 12a.The zinc reagent 2 may also be prepared directly from protected iodoalanine 1 in THF by the Knochel method.Reaction with propargylic tosylates as electrophiles gives rise to the corresponding protected terminal allenic amino acids in 51-81percent yield (four examples); use of enantiomerically enriched propargylic tosylates results in the formation of diastereoisomerically enriched allenic products.Reactions of the zinc/copper reagent 6 with a range of representative electrophiles is explored; use of relatively reactive electrophiles is necessary to obtain satisfactory yields.Finally, the possibility of using the serine-derived iodide 20, in which the carboxylic acid is protected as a methyl ester, is established.This reagent offers advantages over the corresponding benzyl ester protected reagent 6 for the synthesis of unsaturated amino acids.
Preparation of Enantiomerically Pure Protected 4-Oxo-α-amino Acids and 3-Aryl-α-amino Acids from Serine
Jackson, Richard F. W.,Wishart, Neil,Wood, Anthony,James, Keith,Wythes, Martin J.
, p. 3397 - 3404 (2007/10/02)
The organozinc reagent 13, prepared from the protected β-iodo alanine derivative 3c using ultrasonic activation, is efficiently acylated using acid chlorides in the presence of bis(triphenylphosphine)palladium dichloride to give enantiomerically pure protected 4-oxo-α-amino acids 17 in 39-90percent yield (13 examples).Zinc reagent 13 can also be coupled with aryl iodides in the presence of bis(tri-o-tolylphosphine)palladium dichloride to give enantiomerically pure protected phenylalanine analogues 26, 29, and 30 in 10-67percent yield (11 examples).The reaction tolerates the presence of a variety of functional groups in the acid chloride and the aryl iodide and provides derivatives which can be easily deprotected, at either the carboxyl or amino terminus, to give intermediates suitable for peptide synthesis.
