Substrate-controlled product-selectivity in the reaction of the Bestmann-Ohira reagent with N-unprotected isatin-derived olefins.
A mild and efficient reaction of the Bestmann-Ohira reagent with N-unprotected isatin-derived olefins has been developed for the selective synthesis of spiro-pyrazoline-oxindoles and tricyclic pyrazoles. The reaction features an attractive product-selectivity depending on the substituent on isatin-derived olefin. Treatment of 3-aryl/alkylideneoxindoles with BOR afforded spiropyrazoline-oxindoles, whereas 3-phenacylideneoxindoles furnished pyrazoloquinazolinones via a unique ring expansion reaction.
Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India. kishor.mohanan@cdri.res.in.
Ashis Kumar
AK
Gupta
Shakir
S
Ahamad
Ekta
E
Gupta
Ruchir
R
Kant
Kishor
K
Mohanan
D000475:Alkenes / Q000737:chemistry*; D003500:Cyclization; D007211:Indoles / Q000737:chemistry*; D007510:Isatin / Q000737:chemistry*; D015394:Molecular Structure; D063065:Organophosphonates / Q000737:chemistry*; D000078183:Oxindoles; D011720:Pyrazoles / Q000737:chemistry*; D013237:Stereoisomerism
D000475:Alkenes; D007211:Indoles; D063065:Organophosphonates; D000078183:Oxindoles; D011720:Pyrazoles; C022960:2-oxindole; D007510:Isatin