Hay coupling

Potential starting materials for the syntheses of exploded [n]rotanes via approaches B and C containing an even number of cyclopropane units may also be prepared by applying the Hay coupling procedure (Scheme 27) [48, 52]. 

In yet another approach towards the synthesis of cyclocarbons by cycloreversion, Adamson and Rees [71] prepared the 1,2,3-triazole-fused dehydroannulenes 42 - 44, as mixtures of regioisomers in ca. 30 % overall yield, by oxidative Hay coupling of the protected 4,5-diethynyl-l,2,3-triazole 41 (Scheme 7). No investigations have yet been reported on the thermal or mass spectrometric [3-1-2] cycloreversions of 42-44, with loss of the triazole moieties and ultimate formation of the cyclocarbons Cis, C24, and C30, respectively. 

Oxidative polymerization of trans-bis-deprotected 79 under Hay coupling conditions [54] yielded, after end-capping with phenylacetylene, the high-melting and readily soluble oligomers 80a-e with the poly (triacetylene) backbone [87,106] (Scheme 8). Poly(triacetylene)s [PTAs,-(C=C-CR=CR-C=C) -] are the third class of linearly conjugated polymers with a non-aromatic allcarbon backbone in the progression which starts with polyacetylene [PA,... 

Due to an interest in studying their unusual reactivity (vide infra), several attempts were made to maximize yields of the strained dimers 74. Lengthening reaction times and decreasing substrate concentrations in the cyclooligomerization experiments proved fruitless. In response to this situation, a stepwise synthesis of the tetrahexyl-substituted dimer was developed as shown in Scheme 18. Surprisingly, Hay coupling of 77 resulted in an improved yield of the tetramer (45 vs 8 %) and a substantial decrease in the yield of dimer (13 vs 30%). This product distribution was unexpected, since intramolecular reactions are typically much faster than intermolecular reactions. 

The first synthetic approaches to organometaUic dehydroannulenes were not particularly successful, because neither the submission of 22b nor of 29b led to the formation of the desired cyclooHgomers. In the first case only an insoluble, probably polymeric, yellow material was isolated, whereas in the case of 29b decomposition under rapid darkening was observed. Surprised by this behavior, it was decided to subject the much less reactive, sterically more encumbered, bistrimethylsilyl-substituted 22 a to the conditions of the Hay coupling. 

With its two different protective groups, derivative 109 could be selectively depro-tected to the free acetylene 110 that, on Glaser-Hay coupling, furnished the highly unsaturated dimer 111 (72%), probably as a mixture of two diastereomers. Although comparable approaches to prepare derivatives of the parent hydrocarbon 10 and 11 (Scheme 5.1) have so far failed, with the protected 1,1-diethynylallene 112 a first representative of the cross-conjugated diethynylallene 9 could be synthesized [40],... 

Oxidative coupling of terminal acetylenes in the presence of copper(I) catalysts is the best method of preparing symmetrically substituted butadiyne derivatives,5 and has been applied to the coupling of trimethylsilyl-acetylene. Better yields are obtained using the Hay procedure in which the catalyst is the TMEDA complex of copper(I) chloride.7 The procedure submitted here is an improved version of Walton and Waugh s synthesis of BTMSBD by the Hay coupling of trimethylsilylacetylene.2 BTMSBD has also been prepared by... 

The Glaser Coupling (or Hay Coupling) is a synthesis of symmetric or cyclic bisacetylenes via a coupling reaction of terminal alkynes. Mechanistically, the reaction is similar to the Eglinton Reaction the difference being the use of catalytic copper(I), which is reoxidized in the catalytic cycle by oxygen in the reaction medium. 

The related Hay Coupling has several advantages as compared with the Glaser Coupling. The copper-TMEDA complex used is soluble in a wider range of solvents, so that the reaction is more versatile. 

Although the Hay coupling has also been successfully used in the synthesis of cyclic oligoacetylenes (shown in the Section 1.3.3, Scheme 8) [6], for extended, macro-cyclic oligoacetylenes the modification presented by Eglinton and Galbraith [7a] is quite often the method of choice [2]. Here copper(II) acetate must be used in large excess, most commonly dissolved in pyridine or mixtures of pyridine and methanol... 

Table 1. Oligomerization and polymerization of compound 1 by Glaser-Hay coupling. Catalyst formation CuCI, TMEDA, and 02 in 1,2-dichlorobenzene [5, 12]. The reaction was performed in the presence of molecular sieves (4 A). If PhC=CH was available immediately at beginning ofthe coupling process (procedure C) an equal amount was added again 1 h before the end of the reaction. (tr is the total reaction time and tadd is the time until addition of the end-capping reagent.)...

By Pt-TEE scaffolding, the macrocyclic complex 31 (Figure 12) was prepared by deprotection and Hay coupling of dimer 32 [36]. This macrocycle can be envisaged as an expanded... 

Hay coupling of trimethylsilylacetylene BTMSBD has also been prepared by... 

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