US EPA

5094204 

Journal Article 

SYNTHESIS OF 1-AMINO-2-PHENYLETHANE-1-BORONIC ACID-DERIVATIVES 

Matteson, DS; Sadhu, KM 

1984 

1 

Organometallics
ISSN: 0276-7333
EISSN: 1520-6041 

3 

4 

614-618 

English 

10.1021/om00082a019 

WOS:A1984SN19800019 

https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000322228&doi=10.1021%2fom00082a019&partnerID=40&md5=371723883f54f2efe5e7f752a7f8dcb2
Exit
 

The boron analogue of N-acetylphenylalanine, (R)-l-acetamido-2-phenylethane-l-boronic acid (5b), has been synthesized from (+)-pinanediol phenylmethane-1-boronate (lb), which was converted by (dichloromethyl)lithium to the (S)-l-chloro-2-phenylethane-l-boronate (2b), then with V-lithiohexamethyldisilazane to the silylated l-amino-2-phenylethane-l-boronic ester 3b, which was desilylated and acetylated in situ to (+)-pinanediol (R)-l-acetamido-2-phenylethane-l-boronate (4b) and then cleaved to the free boronic acid 5b with boron trichloride. l-Amino-2-phenylethane-l-boronic esters (6) were found to be isolable but unstable, deboronating to 2-phenylethylamine under the influence of heat or hydroxylic solvents. 1-Amino-2-phenylethane-l-boronic acid, though not isolable, partially survives for an hour in cold aqueous solution. Attempts to synthesize the stable α-acetamido boronic esters (4) directly by reaction of lithioacetamide with l-halo-2-phenylethane-l-boronic esters (2) have resulted in a major proportion of O-alkylation to form imino esters. Pinacol l-acetamidino-2-phenylethane-l-boronate (8) has been obtained from the α-iodo boronic ester 2d and acetamidine. © 1984, American Chemical Society. All rights reserved.