Catalytic Asymmetric Allylboration of Indoles and Dihydroisoquinolines with Allylboronic Acids: Stereodivergent Synthesis of up to Three Contiguous Stereocenters

Abstract

The catalytic asymmetric allylboration of cyclic imines with γ,γ‐disubstituted allylboronic acids provides products with adjacent stereocenters in high yield and stereoselectivity. Various electrophiles, including 3,4‐dihydroisoquinolines and indoles, were prenylated in a fully stereodivergent fashion by switching the E/Z geometry of the allylboronate and/or the enantiomer of the BINOL catalyst. 3‐Methylindole provided products with three adjacent stereocenters with high stereoselectivity in one synthetic operation.

Asymmetric Organocatalytic C‐C Bond Forming Reactions with Organoboron Compounds: A Mechanistic Survey

“…The reaction was later extended to the asymmetric organocatalytic allylboration of indoles 128 (Scheme ) . The prenylated products 130 were obtained with high yields and stereoselectivities.…”

Mild and Practical Indole C2 Allylation by Allylboration of in situ Generated 3‐Chloroindolenines

“…The reaction of 5a with commercially available trans ‐crotylboronic acid pinacol ester ( 8b ) cleanly afforded reverse crotylation product 7ab in 69 % yield, nicely comparable to 7aa . Encouraged by this result, we then tested prenylBpin ( 8c ), however, only traces of reverse prenylation product 7ac were obtained . Possibly, the sterically encumbered γ‐position is not sufficiently nucleophilic to attack the in situ‐generated 3‐chloroindolenine under these conditions.…”

Enantioselective Construction of Acyclic Quaternary Carbon Stereocenters: Palladium-Catalyzed Decarboxylative Allylic Alkylation of Fully Substituted Amide Enolates

“…2 The prevailing majority of these methods heavily rely on the use of stereodefined trisubstituted alkenes as substrates for enantioselective allylic substitution, 3 conjugate addition, 4 or nucleophilic allylation reactions. 5 …”