3-Methyl-3/7-indene, asymmetric

Catalytic asymmetric methylation of 6,7-dichloro-5-methoxy-2-phenyl-l-indanone with methyl chloride in 50% sodium hydroxide/toluene using M-(p-trifluoro-methylbenzyDcinchoninium bromide as chiral phase transfer catalyst produces (S)-(+)-6,7-dichloro-5-methoxy-2-methyl-2--phenyl-l-indanone in 94% ee and 95% yield. Under similar conditions, via an asymmetric modification of the Robinson annulation enqploying 1,3-dichloro-2-butene (Wichterle reagent) as a methyl vinyl ketone surrogate, 6,7 dichloro-5-methoxy 2-propyl-l-indanone is alkylated to (S)-(+)-6,7-dichloro-2-(3-chloro-2-butenyl)-2,3 dihydroxy-5-methoxy-2-propyl-l-inden-l-one in 92% ee and 99% yield. Kinetic and mechanistic studies provide evidence for an intermediate dimeric catalyst species and subsequent formation of a tight ion pair between catalyst and substrate. 

The use of (R)-(+)-pro1ine in acetonitrile induced the asymmetric aldol cycllzation of the triketone to the enantiomeric ketol, (-)-(3aR,7aR)-2,3,3a,4,7,7a-hexahydro-3a-hydroxy-7a-methyl-lH-indene-1,5(6H)-dione.10... 

The first real trial of asymmetric polymerization of unsaturated cyclic monomers was reported by Shuerch et al [195]. Cyclic olefins (4,5-dihydro-2-methylfuran, indene, 1-methyl cyclopentene and a-angelica lactone) were polymerized using complexes of BF3 with asymmetric Lewis bases like 1-a-methylbenzyl alcohol, tosyl-1-valine or camphor. 

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