Phenyl phenylethynyl

Representative procedure forthecouplingofan alkenyliodonium tosylate with a Gilman cuprate ( )-(2-bromoprop-1 -enyl)benzene [64] To a stirred suspension of Cp2Zr(H)Cl (0.360 g, 1.4 mmol) in THF (6 mL) was added phenyl(phenylethynyl)iodonium tosylate (0.476 g,... 

The onium transfer reaction between alkynylphenyliodonium tetrafluoroborates and triphenylarsine afforded high yields of 1-alkynyltriphenylarsonium tetrafluoroborates.However, this reaction appeared to be mechanistically at variance with the generally admitted patterns of reactivity of alkynyliodonium salts. Reaction of phenyl(phenylethynyl-2- C)iodonium tetrafluoroborate (88) (99% enriched) led to the arsonium salts (89) with more than 95% of enrichment on the p>carbon atom. Although the Michael carbene pathway was not totally excluded, the ligand coupling pathway seemed therefore more important. 

Photoisomerizations of tetracoordinate 1-alkynylboranes offer some synthetic prospects of unusual significance, namely, an entree into the boracycloprene system (45). Thus, irradiation of lithium tri-phenyl(phenylethynyl)borate in THF and acetolytic work-up gave, in high conversion, a 1 5.6 ratio of biphenyl and c/j-stilbene. The low yield of biphenyl (15%) and hydrogen gas (13%) shows that the cleavage of the path a type (Scheme 5) is minor here. When the photolyzate was treated with DOAc, the isolated cw-stilbene was 45% a,a -dideuterated, 44% a-deuterated, and 11% undeuterated. The principal course of this reaction... 

An alkynyliodonium salt, namely, phenyl(phenylethynyl)iodonium hexafluorophosphate, has been tested for application as cationic photoinitiator [38]. The high activity of phenyl(phenylethynyl)iodonium salt as a photoinitiator was verified by photo differential scanning calorimetry (photo-DSC) experiments in direct irradiation and in photosensitized initiation using 9,10-dibutylanthracene, 2-isopropylthioxanthone and benzophenone as sensitizers [38]. 

Attempts were made to perform heterocyclization with 4-phenylethynyl- and 4-ethynyl-5-aminomethyl-l,3-dimethylpyrazole where, on the one side, a strained six-membered ring can be formed, and, on the other side, the aliphatic amino group is more nucleophilic than the aromatic (Scheme 112). However, all attempts to cyclize the ethynylpyrazole and its phenyl analog failed (86TH1). 

Recently, Tour et al. [47] described attempts to use the Bergman cyclizat produce PPP derivatives starting from substituted endiynes, e.g. poi-. 1,4-phenylene) 22 starting from l-phenyl-hex-3-en-l,5-diyne or the structurally related poly(2-phenyl-1,4-naphthalene) 23 starting from l-phenylethynyl-2-ethynyl-benzene. 

V-[2-(3-Phenylprop-2-ynyloxy)benzylidene]isopropylamine (the structure in ref 95 is incorrect) undergoes a cyclization reaction to A -isopropyl-4-phenyl-l-benzoxepin-5-amine (1, 52% yield) when treated with butyllithium. 2-(Phenylethynyl)benzofuranis formed as a byproduct (4%).95... 

Note Both direct and indirect alkanelyses are illustrated in these examples. 2,3-Bis(p-bromophenyl)quinoxaline (91) with phenylacetylene (2 equiv) gave 2,3-bis[p-(phenylethynyl)phenyl]quinoxaline (92) (PhsP, Cul, EtsN, AcN Me2, 20°C, A, 15 min then (Ph3P)2PdCl2 i, SOX, 10 h 20%). ... 

In the model studies toward the total synthesis of dimethyl sulfomycinamate, Kelly et al. successfully carried out the Stille couplings of oxazolyl triflate 18 with an array of organostannanes [19, 20]. Thus, 2-aryl-4-oxalone 17 was transformed into the corresponding triflate 18, which was then coupled with 2-trimethylstannylpyridine under the agency of Pd(Ph3P)4 and LiCl to provide adduct 19. The couplings of triflate 18 with phenyl-, vinyl- and phenylethynyl trimethyltin all proceeded in excellent yields. Unfortunately, application to the more delicate system in the natural product failed and the oxazole moiety was installed from acyclic precursors. 

When l-[o-(phenylethynyl)phenyl]cyclopropanol-Co2(CO)6 complex (36) is heated at 50 °C in 2-propanol under argon in the presence of DABCO, a completely different product, 3a,4-dihydro-3ff-cyclopenta[a]inden-2-one derivative 40, is produced as a 95 5 diastereomeric mixture in 72% yield. As shown in Scheme 18, not only aryl-substituted alkynyl derivatives, but also alkyl-substituted alkynyl derivatives, give the corresponding cyclopenta[a]inden-2-one derivatives 40 in moderate to good yields. 

Holm determined the enthalpies of formation of a collection of hydrocarbyhnagnesium bromides by reaction calorimetry with HBr in diethyl ether . He also determined the enthalpies of formation in ethereal solution of the magnesium bromide salts of 20 Bronsted acids, HB, by measuring the enthalpies of reaction of the acid with pentylmag-nesium bromide. For those species that were reported in both studies (hydrocarbyl = phenylethynyl, phenyl, methyl, cyclopropyl, cyclopentyl, cyclohexyl), the enthalpies of formation were identical. The values are listed in Tables 3 and 4. 

For the aluminum systems so far described, only the monomer-dimer equilibrium has been observed. For very bulkyl R groups, the monomer predominates for small alkyls, cyclopropyl, and phenyl-bridged species, the symmetrical dimer is the stable form. When the phenylethynyl group is present, this equilibrium is complicated further by the additional feature arising from the different possible types of bridge bonds, which may be described in the following manner ... 

The authors also considered the relative influence of para substitution in the phenylethynyl compared to simply phenyl (i.e., compared to the analogous styrenes). They found that over the four substituents noted above, the stabilization energy from Eq. (6.14) varied by 5.2 kJ mol for phenylethynyl and 7.0 kJ mol for phenyl. Thus, insertion of the acetylene unit between the radical center and the aromatic ring is predicted to decrease the influence of the aryl substituent by only about 25 percent. 

Kinetic studies by Doering and his collaborators at Harvard150-154 based on five sets of chiral 1,2-disubstituted cyclopropanes, with 1-cyano, 2-(phenyl or propen-2 -yl or -(E)-propenyl or phenylethynyl) (3) and 1 -phenyl-2-(propen-2 -yl) (4) substitution, established the ralative rotational propensities of these substituents and tested the proposition that they might be related to substituent moments of inertia. In all of these cases, the balance between one-center and two-center epimerizations from a trans isomer, reflected in (kt + k2) kl2, was fairly constant, ranging from 1.4 1 to 2.1 1. The kinetic advantages for one-center epimerizations at cyano-substituted carbons for the four cases studied were modest and not especially system-dependent the k, k2 ratios were 2.5,2.2,2.4 and 1.8, thus establishing that rotational propensities are not dictated by some simple function of the moments of inertia of substituents. 

MRS1191 3-ethyl-5-benzyl-2-methyl-6-phenyl-4-phenylethynyl-l,4-(+/-)- dihydropyridine-3,5-dicarboxylate... 

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