Organic chemistry alkyne

Tertiary bismuthines appear to have a number of uses in synthetic organic chemistry (32), eg, they promote the formation of 1,1,2-trisubstituted cyclopropanes by the iateraction of electron-deficient olefins and dialkyl dibromomalonates (100). They have also been employed for the preparation of thin films (qv) of superconducting bismuth strontium calcium copper oxide (101), as cocatalysts for the polymerization of alkynes (102), as inhibitors of the flammabihty of epoxy resins (103), and for a number of other industrial purposes. 

Cyclotrithiazyl chloride is also a useful reagent in organic chemistry in the fusion of 1,2,5-thiadiazoles to quinones as well as the synthesis of (a) isothiazoles from 2,5-disubstituted furans and (b) bis-1,2,5-thiadiazoles from A-alkylpyrroles (Scheme 8.4). Alkenes and alkynes react readily with (NSC1)3 to give 1,2,5-thiadiazoles, while 1,4-diphenyl-1,3-butadiene gives a variety of heterocyclic products including a bis(l, 2,5-thiadiazole). ... 

The 1,3-dipolar eyeloaddition, also known as the Huisgen cycloaddition, is a elassie reaetion in organic chemistry consisting in the reaetion of a dipolar-ophile with a 1,3-dipolar compound that allows the produetion of various five-membered heteroeyeles. This reaction represents one of the most productive fields of modern synthetic organic chemistry. Most dipolarophiles are alkenes, alkynes, and molecules possessing related heteroatom functional... 

Alkynes have three general reaction types in organic chemistry the reaction of the terminal C-H bond, the reaction of the C-C triple bond, and reactions at the propargyl position and beyond. This chapter mostly describes the first two types of reactions. 

Transition metal-catalyzed transformations are of major importance in synthetic organic chemistry [1], This reflects also the increasing number of domino processes starting with such a reaction. In particular, Pd-catalyzed domino transformations have seen an astounding development over the past years with the Heck reaction [2] - the Pd-catalyzed transformation of aryl halides or triflates as well as of alkenyl halides or triflates with alkenes or alkynes - being used most often. This has been combined with another Heck reaction or a cross-coupling reaction [3] such as Suzuki, Stille, and Sonogashira reactions. Moreover, several examples have been published with a Tsuji-Trost reaction [lb, 4], a carbonylation, a pericyclic or an aldol reaction as the second step. 

The synthesis of alcohols, ethers, and ketones by metal-catalyzed addition of water or alcohols to alkenes and alkynes is a well-established reaction in organic chemistry. Many regio- and stereoselective modifications of these reactions are known. In contrast, the analogous addition of ammonia or primary and secondary amines to nonactivated alkenes and alkynes has not had a comparable development, in spite of extensive efforts. In this section, we summarize the recent results of amination to unsaturated compounds. 

Enyne metathesis is unique and interesting in synthetic organic chemistry. Since it is difficult to control intermolecular enyne metathesis, this reaction is used as intramolecular enyne metathesis. There are two types of enyne metathesis one is caused by [2+2] cycloaddition of a multiple bond and transition metal carbene complex, and the other is an oxidative cyclization reaction caused by low-valent transition metals. In these cases, the alkyli-dene part migrates from alkene to alkyne carbon. Thus, this reaction is called an alkylidene migration reaction or a skeletal reorganization reaction. Many cyclized products having a diene moiety were obtained using intramolecular enyne metathesis. Very recently, intermolecular enyne metathesis has been developed between alkyne and ethylene as novel diene synthesis. 

Intermolecular-enyne metathesis, if it is possible, is very unique because the double bond of the alkene is cleaved and each alkylidene part is then introduced onto each alkyne carbon, respectively, as shown in Scheme 9. If metathesis is carried out between alkene and alkyne, many olefins, dienes and polymers would be produced, because intermolecular enyne metathesis includes alkene metathesis, alkyne metathesis and enyne metathesis. The reaction course for intermolecular enyne metathesis between a symmetrical alkyne and an unsym-metrical alkene is shown in Scheme 9. The reaction course is very complicated, and it seems impossible to develop this reaction in synthetic organic chemistry. 

Kagan H, Namy JL (1999) Influence of Solvents or Additives on the Organic Chemistry Mediated by Diiodosamarium. 2 155-198 Kakiuchi F, Murai S (1999) Activation of C-H Bonds Catalytic Reactions. 3 47-79 Kakiuchi F, Chatani N (2004) Activation of C-H Inert Bonds. 11 45-79 Kalck P, Urrutigoi ty M, Dechy-Cabaret O (2006) Hydroxy- and Alkoxycarbonylations of Alkenes and Alkynes. 18 97-123 Kanno K, see Takahashi T (2005) 8 217-236 Keen SP, see Gibson SE (n6e Thomas) (1998) 1 155-181 Kendall C, see Wipf P (2005) 8 1-25... 

As an extension of the Heck reaction, Pd-catalyzed hydroarylation of alkynes and alkenes continnes to attract high level of research interest in simple couphng processes and in cyclization reactions. The use of this type of transformation as part of a domino reaction will be of increasing interest. The research in the field of domino reactions is attracting considerable attention in synthetic organic chemistry since it enables the rapid assembly of complex molecirles in one-pot processes. Very elegant examples of palladium-catalyzed cascade processes where a single catalytic cycle entails several sequential bond transformations have been recently reported [la, b, 2a, b, c]. 

In organic chemistry, reduction is defined as a reaction in which a carbon atom forms fewer bonds to oxygen, O, or more bonds to hydrogen, H. Often, a C=0 bond or C=C bond is reduced to a single bond by reduction. A reduction that transforms double C=C or C=0 bonds to single bonds may also be classified as an addition reaction. Aldehydes, ketones, and carboxylic acids can be reduced to become alcohols. Alkenes and alkynes can be reduced by the addition of H2 to become alkanes. 

The 1,2-addition in solid-phase organic chemistry is also known for the addition to alkenes [258], alkynes [120], carbonyl groups [259] and imines [260]. 

The chemistry of metal complexes featuring alkyne and alkynyl (acetylide) ligands has been an area of immense interest for decades. Even the simplest examples of these, the mononuclear metal acetylide complexes L MC=CR, are now so numerous and the extent of their reaction chemistry is so diverse as to defy efforts at a comprehensive review. " The utility of these complexes is well documented. Some metal alkynyl complexes have been used as intermediates in preparative organic chemistry and together with derived polymeric materials, many have useful physical properties including liquid crystallinity and nonlinear optical behaviour. The structural properties of the M—C=C moiety have been used in the construction of remarkable supramolecular architectures based upon squares, boxes, and other geometries. ... 

Ring-closing metathesis of an enyne, which has double and triple bonds in the molecule, is a remarkable reaction which is useful in synthetic organic chemistry. In enyne metathesis, the double bond is cleaved and carbon-carbon bond formation occurs between the double and triple bonds. The cleaved alkylidene part is moved to the alkyne carbon. Thus, the cyclized compound formed in this reaction has a diene moiety [Eq. (6.77)]. The reaction is also called skeletal rearrangement and is induced by Pt, Pd, Ga, and Ru catalysts ... 

Later at the Shanghai Institute of Organic Chemistry I was joined by two research assistants, Yi De Xing and Yong Fan Zhou. As mentioned previously, there was as yet no efficient way to synthesize tribenzo[o,c,e]cyclooctene 25 (see Scheme 7). Furthermore, our research effort in the quest of the angle-strained alkyne 27 was halted at the last dehydrobromination step, from which only 28 and 29 were obtained (Scheme 7). The pen-H-H repulsion of the expected planar 27 was considered to be responsible for its instability. We reasoned that a planar derivative of 27, tailored to eliminate this unfavorable interaction, might sustain some degree... 

Vinyl acetate is one of many compounds where classical organic chemistry has been replaced by a catalytic process. It is also an example of older acetylene chemistry becoming outdated by newer processes involving other basic organic building blocks. Up to 1975 the preferred manufacture of this important monomer was based on the addition of acetic acid to the triple bond of acetylene using zinc amalgam as the catalyst, a universal reaction of alkynes. 

Alkyne metathesis is now shown to be extremely useful in synthetic organic chemistry and growing to be applied extensively. 

Conditions Rh particle/mesitylene (0.1-1 mol%), CO (10-50atm), toluene, 25 °C, 24-48 h. Reprinted with permission from Wiley-VCH Verlag GmbH Co KG by Aronica, L. A. Terreni, S. Coporusso, A. M. Salvadori, P. Silylformylation of chiral 1-alkynes, catalysed by solvated rhodium atoms. European Journal of Organic Chemistry, 2001,22, 4321-4329. 

The sulfur-nitrogen halide (NSC1)3 is also a useful reagent in organic chemistry. For example, alkenes or alkynes react readily with (NSC1)3 to produce 1,2,5-thiadiazoles and the reaction with A-alkylpyrroles gives bis-1,2,5-thiadiazoles. 

Allenes are versatile synthetic precursors in organic chemistry and the synthesis of many natural products involves the use of allenic compounds [27]. However, they have received much less attention than alkenes or alkynes for transition metal catalyzed reactions. The explanation lies in the problems of selectivity that these substrates display as a result of their reactivity and their inherent chirality [28]. 

The hydrogenation of many different alkenes, dienes, polyenes, and alkynes may be catalyzed by homogeneous complex catalysts. Many of the soluble complexes have the ability to reduce one particular unsaturated group in the presence of other reducible groups. The selectivity rather than their universality makes these catalysts particularly useful in synthetic organic chemistry. With careful choice of catalyst and reaction conditions, remarkable selectivities are attainable. Most of the practically useful catalysts work under ambient conditions. 

Carey Organic Chemistry, 9. Alkynes Fifth Edition... 

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