In the presence of tritylperchlorate, 1-O-bromoacetyl-β-D-glucose stereoselectively reacts with alcohols to give the corresponding α-glucosides in good yields. The similar reaction of 1-O-acetyl-β-D-ribose affords the corresponding β-ribosides exclusively, while in the presence of molecular sieves 4A and lithium perchlorate, α-ribosides are prepared predominantly in good yields.
Process for the stereoselective preparation of l-alanyl-l-proline
申请人:Celgene Corporation
公开号:US05424454A1
公开(公告)日:1995-06-13
L-alanyl-L-proline is stereoselectively prepared catalytically hydrogenating an N-(2-iminopropionyl)-L-proline in the presence of a metal hydrogenolysis catalyst and at a pH of less than about 4. Also disclosed are improved processes for production of N-pyruvyl-L-proline in which L-proline and a 2,2-disubstituted propionyl halide are allowed to react at a pH of at least 9 to produce an L-proline intermediate which is hydrolyzed at a pH range of from about 6.5 to about 8.5 to yield N-pyruvyl-L-proline.
Process for the stereoselective preparation of L-alanyl-L-proline
申请人:Celgene Corporation
公开号:US05319098A1
公开(公告)日:1994-06-07
L-Alanyl-L-proline is stereoselectively prepared catalytically hydrogenating an N-(2-iminopropionyl)-L-proline in the presence of a metal hydrogenolysis catalyst and at a pH of less than about 4. Also disclosed are improved processes for production of pyruvylproline in which L-proline and a 2,2-disubstituted propionyl halide are allowed to react at a pH of at least 9 to produce an L-proline intermediate which is hydrolyzed at a pH range of from about 6.5 to about 8.5 to yield N-pyruvyl-L-proline.
Reaktivfarbstoffe und ihre Verwendung zum Färben OH- oder NH-haltiger Materialien
申请人:BAYER AG
公开号:EP0028351A2
公开(公告)日:1981-05-13
ReaktivfarbstoffederallgemeinenFormel
worin R1, R2, K, Y und B die in der Beschreibung angegebene Bedeutung haben, und deren Verwendung zum Färben hydroxylgruppenhaltiger und stickstoffhaltiger Materialien, insbesondere von Textilmaterialien aus nativer und regenerierter Cellulose, aus Wolle, ferner aus Seide, synthetischen Polyamid-und Polyurethanfasern sowie zum Färben von Papier.
通式中 R1、R2、K、Y 和 B 具有说明中给出的含义的活性染料,以及它们在含羟基和含氮材料染色中的用途,特别是在由原生和再生纤维素、羊毛、丝绸、合成聚酰胺和聚氨酯纤维制成的纺织材料中,以及在纸张染色中的用途。
Cephalosporin intermediates and their preparation
申请人:THE UPJOHN COMPANY
公开号:EP0153874A2
公开(公告)日:1985-09-04
@ 3-(Activated ester)methyl-3-cephem 4-carboxylic acids are prepared by the direct reaction of a 3-hydroxymethyl-3-cephem-4-carboxylic acid with an activated-0-ester-methyl forming acylating agent, in the presence of a 4-(tertiary amino) pyridine catalyst and an acid-absorbing base, in a non-polar liquid solvent, at -78 to 30 C. Certain products of the reaction are novel.