Alkynyl derivatives

Alkenyl-substituted diarylnitrilimines 325, generated by photolysis or thermolysis of corresponding tetrazoles 324, undergo a regioselective INIC reaction to yield fused 2-pyrazolines (Scheme 34) [93]. Similarly, with alkynyl derivatives... 

Until 1992, the only ethynylated cyclobutadiene complexes pertinent in the literature were 22 - 24, prepared by Fritch and Vollhardt using [2 -i- 2]-cycloaddition of suitable polyynes over CpCo(CO)2 [24]. No alkynylated derivatives of 25, however, had been prepared. 

The analogous dimerization of alkynes over Fe(C0)5 is not applicable, so clearly a different route towards alkynylated derivatives of 25 was needed. Comparison of 25 to cymantrene suggests that metallation of the hydrocarbon ligand should be the route of choice for the synthesis of novel substituted cyclobutadienes. In the literature, addition of organolithium bases (MeLi, BuLi) to the CO ligands with concomitant rearrangement had been observed [25]. But the utilization of LiTMP (lithium tetramethylpiperidide, Hafner [26]) or sec-BuLi as effectively non-nucleophilic bases led to clean deprotonation of the cyclobuta-... 

Bardaji, M., Lagrma, A. and Jones, P.G. (2001) Reactivity of anAcetylenephosphine Gold(III) Precursor Addition to the Triple Bond or Formation of Alkynyl Derivatives. Organometallics, 20(18), 3906-3912. 

The regiochemistry of the hydrozirconation of disubstituted stannyl- [24, 167-170] and silyl- [171] acetylenes and boron- [118, 172-175] and zinc- [34, 126] alkynyl derivatives result in the formation of 1,1-dimetallo compounds. Hydrozirconation of alkynyliodonium salts affords alkenylchlorozirconocenes with the Zr-C bond geminal to the iodonium moiety [176]. These zirconocene complexes allowed the preparation of ( )-trisubstituted olefins (Scheme 8-20). 

A process similar to that of Scheme 23, but involving 3-alkynyl derivatives of 76, viz. 78, leads to the isomeric series of pyrrolopyrimidopyridazines represented by 79 (Scheme 25) <2003RCB441>, and imidazopyrimidopyrid-azines such as 80 and 81 are similarly accessible via 3-(alkylamino) derivatives of 76 <2003T7669> (Equations 18 and 19). A review of the range and scope of these reactions is available <2005JHC375>. 

The simplest (and smallest) alkali metal alkynyl derivative, ethynyllithium, can only be obtained in the form of single crystals as a base adduct. In the presence of ethylenediamine (en), a polymeric compound as double strands connected by the en donors is obtained, 150.159... 

In addition to these examples, several polynuclear mercury alkynyl derivatives have been prepared. Examples of such derivatives include compounds 50-56 which have been obtained by reaction of the MeHgGl with the primary alkyne in basic methanolic conditions.67,68 The phenyl analogs have also been isolated. Most of these compounds have been characterized by FTIR, NMR, and FABMS, and in the case of 51-53 by single crystal X-ray diffraction. 

The synthesis of multivalent neoglycoconjugates by 1,3-dipolar cycloaddition of nitrile oxides and alkynes has been reported (493). The nitrile oxides have been generated in situ in the presence of alkynyl derivatives, allowing the access to homo and hetero multivalent systems containig O- and C-linked glycosides and isoxazole bridges. 

Dolphin has employed the Sonogashira coupling of terminal alkynes with zinc(II)-10-iodo-5,15-diphenylporphyrin (126) to prepare a series of alkynyl derivatives 127 [87], and similar syntheses of p-alkynyl porphyrins have been described [88]. 

In contrast, an excellent yield was obtained for the reaction between 5-iodoimidazole and propargyl alcohol in the absence of Cul to install the 5-alkynyl derivative [10, 41], The adduct was then deprotected to 5-alkynyl- l-P-D-ribofuranosylimidazole-4-carboxamide 58, an antileukemic agent. It is noteworthy that if the Sonogashira reaction was conducted in the presence of Cul, the yield dropped to 19%. 

A related intramolecular coupling between a monodentate acetate ligand and a transient diphenylallenyhdene moiety was observed when the hydroxo-alkynyl derivative 78 was treated with HPFg, affording the ruthenacycle 79 (Scheme 27) [283],... 

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. 

Alkynyl derivatives of 9-BBN act as mild sources of nucleophilic acetylenic groups. Reaction occurs with both aldehydes and ketones, but the rate is at least 100... 

Ready addition of nucleophiles (Nu ) to metal-allenylidene complexes affords alkynyl derivatives. Subsequent protonation or alkylation, as described in Section 1.2.3 above, then gives the corresponding vinylidene complexes (Equation 1.8) ... 

Reactivity of Substituents Attached to Ring Carbon Atoms 10.11.7.1 Alkyl, Alkenyl, and Alkynyl Derivatives... 

The reactions, usually carried out in organic solvents, proceed under mild conditions and often give high yields of the desired compounds. Compounds in which the hetero-atom bears one alkynyl group are better known than the "poly"-alkynyl derivatives. This can be explained in part by the readier availability of the mono-halogeno compounds R nYX and by a lower... 

In the case of substituted alkynyl derivatives, the 5-exo process was still effective and the stereochemistry of the resulting alkenes was proven to be exclusively Z. 

Vianna EP, Ferreira AT, Dona F, Cavalheiro EA, Silva Fernandes MJ (2005) Modulation of seizures and synaptic plasticity by adenosinergic receptors in an experimental model of temporal lobe epilepsy induced by pilocarpine in rats. Epilepsia 46(Suppl 5) 166-173 Volpini R, Costanzi S, Lambertucci C, Taffi S, Vittori S, Klotz KN, Cristalli G (2002) N(6)-alkyl-2-alkynyl derivatives of adenosine as potent and selective agonists at the human adenosine A(3) receptor and a starting point for searching A(2B) ligands. J Med Chem 45(15) 3271-3279... 

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