Tetraarylmethane derivatives

Dihalothiophenes are also excellent substrates for twofold Heck couplings, even with 1,1-dimethylallene, the products of which can subsequently undergo a twofold Diels-Alder reaction [394]. Even fourfold Heck reactions applying a tetradiazonium salt with a tetraphenylmethane framework have been demonstrated with various alkenes to yield the corresponding fourfold coupled tetraarylmethane derivatives (Scheme 8.64) [395]. 

Scheme 8.64 Fourfold Heck reactions with tetraarylmethane derivatives [395].

Shi et al. [161-164] studied a different reaction of an array of triphenylmethane and triarylmethane derivatives such as alkanes, alkenes, alkynes, phosphonates, phosphonic acids and esters, dialkylamines, triaryl acetic acid, triaryl acetonitriles, triaryl acetates, and tetraarylmethanes and published a review of their work [65]. Mainly from product studies they proposed the special case of di-Jt-methane and oxa-di-7u-methane reactions [165], viz. a,a-elimination gives a biaryl and the corresponding carbenes and operates in polar and nonpolar sol-... 

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