Catalytic Aldol–Cyclization Cascade of 3‑Isothiocyanato Oxindoles with α‑Ketophosphonates for the Enantioselective Synthesis of β‑Amino-α-hydroxyphosphonates

A cascade
aldol–cyclization reaction between 3-isothiocyanato
oxindoles and α-ketophosphonates has been developed for the
synthesis of β-amino-α-hydroxyphosphonate derivatives.
Catalyzed by a quinine-based tertiary amino-thiourea derivative, this
reaction delivers 2-thioxooxazolidinyl phosphonates based on a spirooxindole
scaffold bearing two contiguous quaternary stereogenic centers in
high yields with excellent diastereo- (up to >20:1 dr) and enantioselectivities
(up to >99:1 er).