TCNQ, cycloaddition with

A variety of other highly-strained electron-rich donors also form colored complexes (similar to homobenzvalene) with various electron acceptors, which readily undergo thermal cycloadditions (with concomitant bleaching of the color).209 For example, Tsuji et al.210 reported that dispiro[2.2.2.2]deca-4,9-diene (DDD), with an unusually low ionization potential of 7.5 eV,211 readily forms a colored charge-transfer complex with tetracyanoquinodimethane (TCNQ). The [DDD, TCNQ] charge-transfer complex undergoes a thermal cycloaddition to [3,3]paracyclophane in excellent yield, i.e.,... 

We have reported the first electroactivity of a thioketene dimer compound [116]. The CV measurement of 2,4-dibenzylidene-l,3-dithietane (31), which was prepared by a basic dimerization of phenylthioketene derived from ben-zyltriphenylphosphonium chloride, showed irreversible two-step oxidation peaks at 0.25 and 0.61 V vs Ag/Ag+, indicating that 31 acts as a stronger electron donor than 2,6-bisphenyl-l,4-dithiafulvene (30) and TTF (2). The dimer (31) can form a 1 1 CT complex with TCNQ in DMSO. Cycloaddition polymerization of bisthioketene derived from p-xylenebis(triphenylphosphoni-um chloride) gave a -conjugated polymer (32) with thioketene dimer unit in the main chain (Scheme 12). This polymer was the first polymer contain-... 

In analogy to the cycloaddition of electron-rich alkenes with electron-deficient olefins , cycloadditions between donor-acceptor pairs of cyclopropanes and unsaturated compounds have been obtained. They include for instance the cycloaddition of substituted cyclopropanes with ethylene-tetracarbonitrile (TCNE), (equation 23 ). [10]Paracyclophadienes have been obtained from the reaction of tetrasubstituted 1,2-dicyclopropylethylenes with TCNQ. ... 

The formal 2 -I- 2-cycloaddition reaction of platinum(ll) acetilides (14) with TCNE and TCNQ initially produced 7,7,8,8-tetracyano-p-quinodimethane cyclobuta-1, 3-dienes that undergo retroelectrocyclization to produce feis-cycloadducts (15, 16). In all examples investigated, the triple bond adjacent to the platinum atom did not react with the TCNE or the TCNQ (Scheme 5). The 2-I-2-cycloaddition of substituted cyclobutadiene-AlCl3 complexes (18) with methyl phenylpropynoate (17) produced Dewar benzene intermediates (19) that readily converted to 1,2,3,4-tetramethyl- and 1,2,3,4-tetraethyl-fluorenes (20) (Scheme 6). The first rhodium-catalysed inter-molecular 2-1-2-cycloaddition of terminal alkynes with e-deflcient alkenes yielded substituted cyclobutenes in high yields (99%) and complete regioselectivity. An 8-quinolinolatorhodium/phosphine catalyst (21) was employed in this reaction. ... 

A low molecular weight polymer with alternating ferrocene and dithiafiilvene moieties in the backbone was prepared by cycloaddition polymerization using monomer 145 as shown in Scheme 39." This polymer formed a soluble charge transfer complex with TCNQ, and on doping with iodine polymer 146 had an electrical conductivity of 3.6 X 10 S/cm. 

I-2-cycloaddition reaction of 2(5//)-ffiranones to trialkylsilylacetylenes yielded CM-3-oxabicyclo[3.2.0]hept-6-en-4-ones regioselectively. The 2-i-2-cycloaddition of arylethynyl-2//-cyclohepta[f>]ffiran-2-ones (10) with 7,7,8,8-tetracyanoquinodimethane (TCNQ) (11), in refluxing AcOEt, produced cyclobutene cycloadducts that underwent ring opening to yield dicyanoquinodimethane chromophores (12) in excellent yields (Scheme 4). The photocatalytic intermolecular 2-I-2-cycloaddition reaction of... 

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