The Direct Asymmetric Alkylation of α‑Amino Aldehydes with 3‑Indolylmethanols by Enamine Catalysis

This work describes an efficient α-alkylation reaction of α-amino aldehydes with 3-indolylmethanols. In the promotion of catalyst <b>3f</b>, the target products were obtained in high yields (up to 99%), good diastereoselectivities (up to 88:12), and excellent enantioselectivities (up to 96% ee). The direct alkylation products can be readily converted into other tryptophan derivatives without the loss of stereoselectivities

Catalytic Asymmetric Nucleophilic Addition of 3‑Vinyl Indoles to Imines

The 3-vinyl indole is used as a nucleophile to react with aromatic and aliphatic imines. Chiral 3-substituted indoles bearing multiple functional groups are produced with up to 99% yield, a 98:2 <i>E</i>/<i>Z</i> ratio, and 97% ee. A possible mechanism is proposed to explain the observed stereoselectivities. This strategy provides an efficient way for the preparation of novel chiral 3-substituted indoles

Chiral Calcium Phosphate Catalyzed Asymmetric Alkenylation Reaction of Arylglyoxals with 3‑Vinylindoles

A highly efficient alkenylation reaction of arylglyoxals with 3-vinylindoles catalyzed by chiral calcium phosphate is described. Structurally diverse allylic alcohols bearing indole and carbonyl units are prepared in excellent yields, good diastereoselectivities, and high to excellent enantioselectivities. These products are good building blocks for the synthesis of polysubstituted chiral tetrahydrocarbozol-2-ones. The mechanism study indicates that the most likely role of the catalyst is to activate the hydrate of arylglyoxal and control the stereoselectivity via desymmetric coordination