Alkynyl functionalized

With the alkynyl functionality greater than two, starbust type complexes are obtained, as derived, for example, from 1,3,5-trialkynylbenzenes 85 or -triazines,86 1,1,2,2-tetraalkynylethenes,85 or bis(l,2-dialkynyl)phenylene-bridged crown ethers or calixarenes. ... 

In another example, Hg(OTf)2 has been used for the stereoselective ring expansion of 116 to 117 with excellent stereospecificity for the (Z)-isomer (Equation (43)).156 Carbomercuration reactions have also been observed for derivatives such as 118, which possesses both an allylic silane as well as an alkynyl functionality. For 118, the reaction affords the 5-m -ring compound 119 as the (Z)-isomer. Formation of the (/. )-isomcr is disfavored because the bulk of the TMS group precludes an anti-attack (Equation (44)).157... 

The reaction of tetraethynylplatinum derivatives with mercury dihalide in acetone affords complexes 156 and 157 in which the mercury centers are coordinated to two neighboring mercury alkynyl functionalities.194 195 In turn, each alkynyl functionality interacts with the mercury center in an 7]Z-fashion. For complexes 156 and 157, the resulting Hg-Cjp bonds, which range from 2.41 to 2.77 A, are longer than typical Hg-C cr-bonds but shorter that those observed in 154. In 156, the greater flexibility of the structure allows for the formation of shorter Hg-C(.r/>) bonds than in 157 (av. Hg-C(.r/>) = 2.52 A for 156 and 2.64A for 157). The formation of such complexes is not limited to the case of... 

Using NaOH as the base, diarylacetylenes have been synthesized from either 2-methyl-3-butyn-2-ol [121] or trimethylsilylacetylene [122], In both cases, NaOH unmasked the protections after the first coupling reaction, revealing the additional terminal alkynyl functionality. Therefore, coupling the adduct 141, derived from 2-iodothiophene and 2-methyl-3-butyn-2-ol, with 2-iodobenzothiophene provided diarylacetylene 142 [121], Analogously, dithienylacetylene (143) was obtained when 2-iodothiophene and trimethylsilylacetylene were subjected to the same conditions [122],... 

When the two alkynyl functions are separated by a sUyl or a phosphano group, an interesting rearrangement takes place giving rise to tricyclic species (Scheme 30). This skeletal rearrangement proceeds via intermediate zwitterionic zirconate (102). The empty orbital and electrophilicity of Zr are probably the reasons that lead to zwitterionic species containing zirconates and carbocationic centers. 

Recently, we reported the use of the bis(alkynyl)titanocene complex [(r/5-C5H4SiMe3)2Ti(C=CSiMe3)2] as a molecular tweezer that functions as a bi-dentate ligand by using the two alkynyl functions to coordinate to a single cop-... 

The alkynyl functional group has only a very weak deshielding effect on the C—1 and C—2 carbons (C1 =+4.4ppm, C2=+6.0ppm). It displays a similar shielding effect on the alpha carbon of the alkynyl benzenes. 

They also found that only the first generation of azido terminated dendrimers successfully cross-linked the hydrophilic shell of the alkynyl functionalized micelles and that is because of the hydro-phobic nature of the dendrimer of generations greater than one that is proved to be incompatible with the hydrophilic nature of the micelle corona within the aqueous reaction conditions, and as a result did not behave as effective cross-linkers. They exploited this incompatibility by changing... 

FIGURE 54.11 Synthesis of polymer nanoparticles from alkynyl-functionalized micelles and azido-terminated dendrimers. (FromNew J. Chem., 31(5), O Reilly, R.K., Joralemon M.J., Hawker C.J., and Wooley K.L., Preparation of orthogonally-functionalized core click cross-linked nanoparticles, 718-724. Copyright 2007. Reproduced by permission of The Royal Society of Chemistry.)... 

Stimuli responsive flexible chains have been combined with fluorine-based rods. A thermally responsive rod-coil poly[poly (N-isopropylaaylamide)-f7-PF-b-poly(N-isopropylacrylamide)] triblock copolymer has been successfully synthesized through ATRP from an end-functionalized macroinitiator. The multifunctional sensory properties of amphiphilic poly[2,7-(9,9-dihexylfluorene)]-Mocfe-poly[2-(dimethylamino)ethyl methacrylate] (PF-1 -PDMAEMA) rod-coil diblock copolymers were reported for different PDMAEMA coil lengths. Thermoresponsive conjugated rod-coil-coil triblock copolymers were prepared from terminal azido-functionalized poly(N-iso-propylacrylamide)-b-poly(N-hydroxyethylacrylamide) (PNIPAAm-b-PHEAA) and alkynyl-functionalized PF via a click reaction. The azido-functionalized PNIPAAm- 7-PHEAA copolymers with different block ratios were prepared by ATRP from an initiator bearing the azide group, whereas alkynyl-functionalized PF was synthesized by Suzuki coupling. ... 

The alkynyl functionality of alkynones 1 is perfectly suited for subsequent copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) in the sense of an MCR (2015ASC(357)617). A microwave-assisted three-component reaction of aroyl chlorides 4, TMS-substituted acetylene (5a), and benzyl azide (10a) consisting of modified Sonogashira cross-coupling I, desilylation, and CuAAC furnishes 4-disubstituted 1,2,3-triazoles 11 in moderate to excellent yields (Scheme 5) (201 OOL(12)4936). 

Reactions at a jSy-alkynyl function in an acetylenic sulphone (140) give products indicating the influence of the sulphonyl group, e.g. the formation of the vinyl sulphone (141), which gives j8-keto-sulphones through cleavage of the oxetan ring at different points on acid hydrolysis. 

In this vein, alkynyl-functionalized (hetero)arenes were utilized in Pd-catalyzed arylation and cyclization events to reach tetrasubstituted alkenes. This strategy proved successful with an iV-phenylpropiolamide (Scheme 18a) [240] and N-(2-alkynylbenzyl)indoles (Scheme 18b) [241]. Copper catalysis was also viable, as demonstrated in reactions with 2-ethynyl anilides to yield benzoxazines (Scheme 18c) [242]. A copper-catalyzed carboarylation of electron-rich alkynes... 

NIS-promoted iodocarbocychzation reaction of various functionalized 1,5-enynes occurs via a 5-endo diastereoselective process to form iodo-functionalized cyclopentenes (Scheme 6.22). Initially, the iodonium ion activates the alkynyl functionality through jt-coordination. Upon nucleophilic attack of the alkenyl moiety in an anti fashion, an iodocyclization reaction occurs and a carbocation is formed. Further, proton abstraction by the succinimide anion affords the iodo-functionalized cyclopentenes [26]. 

A vast number of liquid crystals showing nematic or other mesophases are obtained using benzene, biphenyl or terphenyl units as core systems, often with the rings connected by polarizable linkages such as ester or alkynyl functions or direct-... 

Suitable crosslinking chemistiy for the hb-PPh with reactive alkynyl functionalities derived from the AB2 approach, utilizing azide-alkyne click reaction by 1,3-dipolar cycloaddition, was utilized to check the suitability of such polymers as dielectric material in microelectronics. For polymers to be used for optoelectronic... 

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