A regioselective formal [4+2] cycloaddition reaction of nitrostyrene derived MBH alcohol and 2‐arylidene‐1,3‐indanedione resulted in functionalized tetrahydrospiropyran derivatives with excellent chemical yields (up to 93 %). The reaction tolerated various electron rich and electron deficient substituents on the aryl group of 2‐arylidene‐1,3‐indanedione as well as MBH alcohol. The utility of MBH alcohol as an ambident substrate, which is performing the dual role of nucleophile and electrophile with 2‐arylidene‐1,3‐indanediones was successfully demonstrated for 20 derivatives. A single isomer was obtained exclusively in all the products via cascade process which followed an oxa‐Michael–Michael addition sequence using cesium carbonate as base. Control experiments were carried out to understand the mechanistic details of the reaction. These experiments prove that the reaction undergoes a stepwise pathway rather than a concerted mechanism.
Dedicated to Prof. Kwunmin ChenA sequential formal [4 + 2] cyclization involving cascade protocol has been developed for the construction of multisubstituted six-membered spirocyclic scaffolds by using 2arylidene-1, 3-indanedione and nitro allylic alcohol. This method generates four stereocenters in spiropyran ring with high diastereoselctivity (99 : 1) under mild reaction conditions.
A [3+2] annulation protocol for the construction of functionalized spirocyclopentenes utilizing 1,3-indanedione derived benzylidene-1,3-indanedione and ethyl-2,3-butadienoate at room temperature was developed.
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