ISSN:
0018-019X
Schlagwort(e):
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Homogeneous asymmetric hydrogenation of a wide range of methyl and tert-butyl (Z)-2-(acylamino)-3-(heteroaryl)acrylates (see 1a-f and 2a-d, f, g, resp.) catalyzed by diphosphinerhodium catalysts was studied for the synthesis of enantiomerically pure 3-furyl-, 3-thienyl-, and 3-pyrrolylalanines (see 3a-f, and 4a-d, g; Scheme 1). The precursors, the (Z)-α-amino-α,β-didehydro esters 1a-f and 2a-d, f, g were prepared in high yields using the phosphorylglycine-ester method (Scheme 1). Isomerically pure (Z)-α-amino-α,β-didehydro esters were required to obtain the highest enantiomeric excesses (ee's) in the asymmetric hydrogenation, and the tert-butyl-ester strategy was beneficial in terms of both getting pure (Z)-α-amino-α,β-didehydro esters and obtaining high ee's in the hydrogenation. Finally, in contrast to the methyl-ester series, deprotection of the tert-butyl esters 4a-d, g was easily performed using CF3CO2H without any racemization.
Zusätzliches Material:
4 Tab.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/hlca.19940770518
