General Synthesis of C-Glycosyl Amino Acids via Proline-Catalyzed Direct Electrophilic α-Amination of C-Glycosylalkyl Aldehydes
摘要:
Non-natural axially and equatorially linked C-glycosyl alpha-amino acids (glycines, alanines, and CH2-serine isosteres) with either S or R alpha-configuration were prepared by D- and L-proline-catalyzed (de > 95%) alpha-amination of C-glycosylalkyl aldehydes using dibenzyl azodicarboxylate as the electrophilic reagent.
The electrophilic ring opening of donor‐acceptor spiro‐cyclopropanecarboxylated sugars are shown to provide easy access to the stereoselective synthesis of β‐C‐glycosyl D‐ and L‐alanine derivatives. A possible mechanism is proposed for the ring‐opening reaction based on the obtained crystal structure of one of the spiro‐cyclic sugar moieties.