181770-37-6Relevant articles and documents
154. Asymmetric synthesis of 3-hydroxyprolines by photocyclization of C(1′)-substituted N-(2-benzoylethyl)glycine esters
Steiner, Andre,Wessig, Pablo,Polborn, Kurt
, p. 1843 - 1862 (1996)
The chiral N-(2-benzoylethyl)-N-tosylglycine esters 5a-h and the α -amino-γ-keto ester 6 were prepared from γ-(tosylamino) alcohols 7a-h. Irradiation of compounds 5a-c, e gave cis-3-hydroxyproline esters 20-23 (Scheme 6), partly with complete asymmetric induction by the C(1′)-substituent, whereas 6 gave enantiomerically pure 4-hydroxy-4-phenyl-L-proline esters 24 in good yield but low de (Scheme 6). The de of the photocyclization depended on the nature and/or size of the C(1′)-substituents. Irradiation of ketones 5d and 5f, bearing H-atoms at C(γ) with respect to the keto function, gave cyclobutanols (Scheme 9) in low yields besides the preferred Norrish-type-II cleavage product. Cyclopentanol 25 was a by-product of the photocyclization of 5c as a result of H-C(δ) abstraction from the t-Bu group The structure of products 20, 22, and 24a, b was established by NMR or X-ray analyses.
A Simple Approach to β-Amino Acids by Acylation of Arenes with N-Acyl Aspartic Anhydrides
Griesbeck, Axel G.,Heckroth, Heike
, p. 1243 - 1244 (2007/10/03)
Friedel-Crafts acylation of arenes (benzene, toluene, o-xylene) with N-protected (Bz, Ac, Ac-Bn, Ts, Tfac, N,N-Pht) aspartic anhydrides (1a-1f) resulted in mixtures of α- and β-amino acids. The β/ α-selectivity could be optimized for alkylated arenes (toluene, xylene) and the N-Ac, N-Bn protected 1c.
