Pyridine Core Activation <i>via</i> 1,5-Electrocyclization of Vinyl Pyridinium Ylides Generated from Bromo Isomerized Morita−Baylis−Hillman Adduct of Isatin and Pyridine: Synthesis of 3-Spirodihydroindolizine Oxindoles
5-electrocyclization of vinyl pyridiniumylides generated from bromo isomerized Morita−Baylis−Hillman adducts of isatin and pyridine under basic conditions. The method has been successfully applied for an efficient synthesis of a number of 3-spirodihydroindolizine-2-oxindoles, which have been found as core structure of secoyohimbane and heteroyohimbane alkaloid natural products.
Efficient construction of a challenging aza-spirocycloheptane oxindole scaffold is reported through an unprecedented [4 + 3] cycloaddition reaction with bromo-substituted Morita–Baylis–Hillman adducts of isatins and N-(ortho-chloromethyl)arylamides. Both reactive intermediates, the allylic phosphonium ylides and aza-o-quinone methides, were in situ generated, chemoselectively facilitated by a Lewis
A Short and Efficient Synthesis
of 3-Spiro-α-methylene-γ-butyrolactone Oxindolones
from Isomerised Bromo Derivatives of Morita-Baylis-Hillman Adducts
作者:Ponnusamy Shanmugam、Baby Viswambharan
DOI:10.1055/s-0028-1083549
日期:——
A short and efficientsynthesis of α-methylene-γ-butyrolactone-3-spirooxindolones by the reaction of isomerised bromo derivatives of Morita-Baylis-Hillmanadducts of isatin and formaldehyde followed by acid-catalysed lactonisation has been achieved. The oxindolidino allyl bromide has been used for the first time for the allylation of aldehydes to afford a 2-oxindolidino homoallylic alcohol which on
Synthesis of Oxindole-Appended Allyl Amines and Vinyl Aziridines via InCl3/ArSH-Mediated Ring Opening of Vinyl Aziridines and Sulfur Ylide Aziridination
allyl amines and 3-vinylaziridine-2-oxindoles have been accomplished in good yield via InCl 3 /ArSH-mediated ring opening of 3-vinylaziridine-2-oxindoles and sulfurylideaziridination, respectively. The sulfurylide was generated in situ from the bromo isomerized Morita–Baylis–Hillman adduct of isatin with N -tosyl imines and tetrahydrothiophene under basic conditions.