Template Glaser coupling

Figure 1-6 Template efficiency parameters for the tetrapyridylporphyrin templated Glaser coupling of two zinc porphyrin dimers, in dichloromethane.

Fig. 1 Templated Glaser coupling of bis-alkynyl porphyrin 1 in the presence of BIPy and PyaT.

Sanders and coworkers have shown that the interaction between pyridine and Zn-porphyrins can be used for controlling the outcome of the Glaser coupling of 62. They were able to show that ethynylphenyl-substituted Zn-porphyrins can be cyclodimerized or cyclotrimerized, depending on the specific pyridyl template present in the reaction medium [28], With 4,4 -bipyridene (63), the cyclodimer 64 was obtained in 70% yield, whereas the presence of 1,3,5 -tris (4-pyridyl) -triazine (65) supports the formation of the cyclotrimer 66 (50%) (Scheme 6.10). 

Scheme 6.20 Synthesis of a macrocyclic bissulfonate by template-supported Glaser coupling.

Figure 9 Active metal template synthesis of [2]catenanes (a) schematic of theory and (b) example of synthesis nsing Glaser coupling.

Metal coordination also enables organic ligands to be used as templates. Sanders and co-workers have synthesized cyclic porphyrin oligomers using Glaser-Hay coupling [16,40]. This reaction oxidatively combines two terminal acetylenes to give a 1,3-buta-diyne link. The syntheses of cyclic porphyrin dimer 38 and trimer 39 were effectively templated by 4,4 -bipyridine 37 and tripyridyltriazine 22, respectively (Scheme 1-10). 

As described in Section III.A.2, Sanders and McCallien assembled four Zn(II) dioxoporphyrins bearing acetylenic groups on the tetrakis(4-pyridyl) porphyrin template 61. They subsequently submitted the complex to the Glaser-Hay coupling reaction which produced the cyclic tetramer in 70% yield. Without a template, the same reaction was not so selective it afforded the tetramer and trimer species in 40%... 

Recent advances in the chemistry of metal-containing knots include the preparation of composite and heteronuclear knots. The composite knots are based on copper templates and phenanthroline ligating moieties, this time linked by alkynic coupling (Glaser) reactions. Despite their complexity, with a minimum of six crossing points in planar representation (Figure 4-28), these species have been fully... 

Figure 10. Synthesis of linear octamer SiiZngll by Glaser-Hay coupling of a mixture of linear tetramers (R = H, SiMes) using 11 as scavenging template.

The recent work of Diederich/ Haley,Roger,de Meijere and Scott,Fallis, Bunz, and several others has established Glaser-type couplings as the preeminent synthetic route to a multitude of complex cyclic polyacetylenes. A limited selection of these molecules is illustrated here, 69-76. Hdger has pointed out that copper salts may act as a template in the intermolecular dimerization of functionalized bisacetylenes. The trimer corresponding to 74 is isolated in 9%. Annulene 76 is unusually stable, being sterically protected by the bulky trimethylsilyl groups. ... 

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