Applications of the Original Yonemitsu Trimolecular Condensation

SCHEME 13.74 Yonemitsu reaction for the synthesis of 3,4-furanone annulated tetrahydro-p-carbolines 336. 

A similar reaction procedure with various sugar-derived aldehydes was published by Sapi et al. in 2010 [129]. Deprotection of the oxygen-substituents present in the aldehyde moiety led to the previously discussed decarboxylative cyclization in one additional step providing the desired products in good yields over two steps with high diastereoselectivity. 

In 2012, Kumar et al. reported the Yonemitsu condensa-tion/decarboxylative cyclization sequence in a saccharine-derived ionic liquid at rt, which provides the products in high yields around 90% [130]. The ionic liquid was shown to be recyclable up to four times with only small decrease in the 

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