2-Phenylaspartic acid derivatives from .beta.-lactams

Abstract

Acknowledgment.-We are indebted to Mr. Osborne P. Crews, Jr., and his staff for the large-scale preparation of intermediates and to Dr. Peter Lim and his staff for the spectra and paper chromatography.

C- and N-Selective Grignard Addition Reactions of α-Aldimino Esters in the Presence or Absence of Zinc(II) Chloride: Synthetic Applications to Optically Active Azacycles

“…We next examined regio-and diastereoselective alkyl and aryl addition to 11, which has a bulky chiral 8-phenylmenthyl (R*) ester 13,14 (Table 2). As expected, the desired C-alkyl addition proceeded smoothly when alkylzinc(II)ate reagents were used (method A), and the corresponding (S)-C-adducts (12) were obtained as sole products with perfect diastereoselectivity (>99:1). Remarkably, alkylzinc(II)ate, method A, was highly effective with various Grignard reagents, such as ethyl (entry 1), isopropyl (entry 3), cyclopropyl (entry 5), tert-butyl (entry 7), benzyl (entries 9 and 11), homobenzyl (entry 14), and octyl (entry 17) magnesium halides.…”

“…PMP protection in 8 was readily cleaved by (NH 4 ) 2 [Ce­(NO 3 ) 6 ] (CAN), and β-lactam 9 was obtained in 92% yield. Ring opening of 8 by NaOMe gave the synthetically useful α-phenyl aspartic acid derivative 10 in 47% yield.…”

Photochemistry of dihydromayurone. Novel solvent participation in a photoisomerization

“…The absence of rapid formation of isomeric ketones 2 and 3 without the presence of a hydrogen-donating spectrum of 7 is identical with that of 2 except for the vinylic region. Ketone 7 has one vinylic hydrogen at 5.65-6.13 (m), one-half of a terminal vinylic hydrogen at 5.21 (d, «/ = 11 Hz, cis coupling), and one-half of a terminal vinylic hydrogen at 4.90 (d, J = 18 Hz, trans coupling).…”

“…These experiments not only show an exchange of hydrogen during the isomerization of 1 or 6 to 2, but the location of deuterium in 7 mechanism6 to be proposed for the formation of 2 and 3 (Scheme II). The other products can also arise from the same radicals 10 and 11.…”

Sterically controlled syntheses of optically active organic compounds. XV. Synthesis of optically active aspartic acid through .beta.-lactam

“…The cyclization of diethyl N-phenyl-A-chloroacetamidomalonate (I) to 0-lactam (II) has been reported by Sheehan and Bose.2 Hydrolysis and decarboxylation of the 0-lactam yielded N-phenylaspartic acid (III). 7 reported the synthesis of A,2-diphenylaspartic acid in a similar way from 0-lactam that was formed by cyclization of 2V-chloroacetyl-IV,2-diphenylglycine ethyl ester. The preparation of 0-lactams is summarized in a review by Sheehan and Corey.8 In the present study, the 0-lactams were prepared from IV-alkyl-V-chloroacetamidoacetonitriles by the cyclization reaction.…”