Lithiated tetrathiafulvalenes, reactions

The reactions of formaldehyde with lithiated tetrathiafulvalenes 8 (79JOC1476) and 16 (88MI3) lead to the corresponding alcohols (Scheme 48). It is worth noting that a much improved synthesis of 27 has recently been described (94S489). 

The formation of TTF—Te bonds is carried out by reacting lithiated tetrathiafulvalenes with elemental tellurium. Two very surprising reactions that tetralithiated TTF undergoes have been described (88TL6177 92CC1048) (Scheme 58). A detailed structural and electronic study of these two donors has recently been reported (93CM1199). 

In the course of exploring new synthetic routes to extended tetrathiafulvalene (TTF) derivatives, lithiation of S,S-acetals, followed by reaction with CS2 and PhCOCl, gave a-dithiomethylenes, which are possible versatile intermediates to extended TTFs. 1,2,3,5,6-Pentathiepanes 86 (Figure 25) were prepared from these intermediates <1995MI1>. 

The chemistry of TTF derivatives has only recently undergone major developments. The lithiation of tetrathiafulvalenes (Section II.B.3) undoubtedly constitutes the most significant development, because the met-allated species formed give rise to a wealth of new derivatives (Section II.C.6), many of which bear functional groups that are amenable to further synthetic elaboration (Section II.C). In contrast, very few examples of the reactions of tetrathiafulvalenes with either electrophiles (Section II. B. 2) or radicals (Section II.B.4) are known, and reports on [2 + 2]- and [4 + 21-cycloadditions of TTF are scarce (Sections II.B.l and II.B.5). Thus, the chemistry of tetrathiafulvalenes is dominated by the introduction and modification of substituents, whereas investigation of the reactivity of the ring atoms is relatively undeveloped. 

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