Diyne-diyls

The use of the unusual spacer, -hex-3-ene-l,5-diyn-diyl, has been reported recently for the construction of polymetallic assemblies (105 R= H, OMe X = H, Ru2(X-ap)4>. Voltammetry experiments were used to confirm the conjugation through the unsaturated spacer and the materials were found to show promising magnetic and (molecular wire) charge-transfer properties. 

A hydrosilylation/cyclization process forming a vinylsilane product need not begin with a diyne, and other unsaturation has been examined in a similar reaction. Alkynyl olefins and dienes have been employed,97 and since unlike diynes, enyne substrates generally produce a chiral center, these substrates have recently proved amenable to asymmetric synthesis (Scheme 27). The BINAP-based catalyst employed in the diyne work did not function in enyne systems, but the close relative 6,6 -dimethylbiphenyl-2,2 -diyl-bis(diphenylphosphine) (BIPHEMP) afforded modest yields of enantio-enriched methylene cyclopentane products.104 Other reported catalysts for silylative cyclization include cationic palladium complexes.105 10511 A report has also appeared employing cobalt-rhodium nanoparticles for a similar reaction to produce racemic product.46... 

Similar polymers containing a single coordinated C=C moiety in the repeat units of poly[(methylphenylgermylene)diyne] and poly[(2,5-diphenyl-l-silacyclopenta-diene-l,l-diyl)diyne] were also prepared. 

Regioselective hydrosilylation of poly[(dimethylsilylene)but-l,3-diyne] (296a) with HSiEt3 using Rhg(CO)i6 as the catalyst at 40 °C gives poly[2-(triethylsilyl)(dimethyl-silylene)but-l-en-3-yne-l,4-diyl]294. In a similar manner, the reactions of poly[(silylene)... 

Thermal reaction of two alkyne groups forms the basis of the Bergmann rearrangement, in which l,5-diyne-3-enes form arene-l,4-diyls (69). The reaction rate is influenced by the radical trapping agent used ". ... 

Ni-alkyne bonding consists of contributions from both the 77, 7t- and cr,diyl tautomers. This bonding picture helps visualize the insertion reactions with alkynes, alkenes, and CO that result in the formation of metallacycles. Thanks to such insertion reactions, Ni-alkyne species are active intermediates in a number of catalytic applications such as alkyne oligomerization, carbonylation, and insertion of heterocumulenes such as CS2 and GO2. For example, a recent example of a C02-fixation reaction involved the stoichiometric, alkylative or arylative carboxylation of alkynes to give a,(3- and / ,/ -unsaturated carboxylic acids. Ni(0)-alkyne complexes have also been used as pre-catalysts in the addition of hydrosilanes to alkynes. In most cases, monoalkynes react to give the products of m-addition, whereas diynes produce enynes (1,2-addition), allenes (1,4-addition), or 1,3-butadienes (1,2,3,4-addition). ... 

Scheme 20 The synthesis of l,l -(buta-l,3-diyne-l,4-diyl)bis[(15)-l -anhych 0-2,3,4,6-tetra-C)-benzyl-D-glucitol] and thoice l,l -(thiophene-2,5-diyl)bis[(lS)-l,5-anhydro-2,3,4,6-tetra-0-benzyl-D-glucitol] [39]...

Besides compound 177 clusters of formula [Ru4( 4- 77 77 7 -RCHC2CHR)(CO)i2] (R = Me, SiMc3, Ph 184) are also formed in the reactions of [Ru4(/t-H)4(CO)i2] with the 1,3-diynes RC2C2R (Equation (132)). In this case, 1,4-hydrogenation of the diyne has taken place to give a l,3-diene-2,3-diyl ligand bound to the RU4 butterfly in a 1x4-arrangement. 

Poly(laCtic acid-eo-glyeolic add) (1 1 to I 3) Poly(oxysuccinoyloxy-2,2-dimethyl-1,3-propylene) Poly(oxysuccinoyloxydoeicosan- lo, 12-diyne-l, 22-diyl) Poly(oxysebacoyloxyhexamethylene), Poly(hexa-methylene sebacate)... 

R = 4-hydroxy-1, 3-phenyleneisopropylidene-4-hydroxy-1,3-phenylene R = ethylidenecarbonyloxysebacoyloxy-oarbonylethylidene, < 40% imide R = hexa-2,4-diyne- 1,6-diyl... 

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