Organocatalytic enantioselective hydroxymethylation of oxindoles with paraformaldehyde as C1 unit.
A bifunctional thiourea-tertiary amine-catalyzed asymmetric hydroxymethylation of 3-substituted oxindoles using paraformaldehyde as the C1 unit was developed. A wide scope of oxindoles, bearing C3 sterically congested quaternary carbon centers, were smoothly obtained in good to excellent yields (up to 99%) and high enantioselectivities (up to 91% ee) under mild reaction conditions. A more significant feature of this approach employs cheap and readily available paraformaldehyde as a hydroxymethylation C1 unit, which is activated by chiral bifunctional thiourea organocatalysts.
Liu
Xiong-Li
XL
Key Laboratory for Asymmetric Synthesis & Chirotechnology of Sichuan Province, Chengdu Institute of Organic Chemistry, Beijing 100049, China.
Liao
Yu-Hua
YH
Wu
Zhi-Jun
ZJ
Cun
Lin-Feng
LF
Zhang
Xiao-Mei
XM
Yuan
Wei-Cheng
WC
D002384:Catalysis; D005557:Formaldehyde / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D008745:Methylation; D015394:Molecular Structure; D000078183:Oxindoles; D011108:Polymers / Q000737:chemistry*; D013237:Stereoisomerism; D013890:Thiourea / Q000737:chemistry
D007211:Indoles; D000078183:Oxindoles; D011108:Polymers; C022960:2-oxindole; D005557:Formaldehyde; D013890:Thiourea; C003043:paraform