ChemInform Abstract: Simple and Stereocontrolled Preparation of Benzoylated Phenylalanine Using Friedel—Crafts Reaction in Trifluoromethanesulfonic Acid for Photoaffinity Labeling.

Abstract

Labeling. -The stereocontrolled Friedel-Crafts benzoylation of chiral phenylalanine derivatives is described. The products can be used in photoaffinity labelling studies. The photolysis of (VIII) is reported. -(MURAI, Y.; WANG, L.; MUTO, Y.; SAKIHAMA, Y.; HASHIDOKO, Y.; HATANAKA, Y.; HASHIMOTO*, M.; Heterocycles 87 (2013) 10, 2119-2126, http://dx.doi.org/10.3987/COM-13-12815 ; Grad. Sch. Agric., Hokkaido Univ., Kita, Sapporo 060, Japan; Eng.) -M. Bohle 06-082

Trifluoromethanesulfonic Acid as Acylation Catalyst: Special Feature for C- and/or O-Acylation Reactions

“…One of these potential photophores is directly constructed from the benzophenone moiety on phenylalanine using a Friedel-Crafts reaction. Due to the low solubility of phenylalanine derivatives in organic solvents for direct C-acylation [49], neat TfOH was used [50]. The neat TfOH catalytic system enabled the direct construction of a benzophenone moiety on optically pure phenylalanine via stereocontrolled Friedel-Crafts acylation (Scheme 6a).…”

“…The strategy for the synthesis of homophenylalanine or bis-homophenylalanine containing TPD moiety starts with the introduction of a TPD moiety in anisole 71 into an aspartic acid analogue 66a [48] or a glutamic acid analogue 66b [46] (Scheme 6b). In this reaction, high temperatures can result in the decomposition of the starting material 71 due to the thermolability of TPD under strongly acidic conditions [50,54]. A temperature of 0 • C is optimal for synthesis using these valuable heat-sensitive aromatic compounds.…”