Alkynes aldehyde synthesis

Because organophosphorus compounds are important in the chemical industry and in biology, many methods have been developed for their synthesis [1]. This chapter reviews the formation of phosphorus-carbon (P-C) bonds by the metal-catalyzed addition of phosphorus-hydrogen (P-H) bonds to unsaturated substrates, such as alkenes, alkynes, aldehydes, and imines. Section 5.2 covers reactions of P(lll) substrates (hydrophosphination), and Section 5.3 describes P(V) chemistry (hydrophosphorylation, hydrophosphinylation, hydrophosphonylation). Scheme 5-1 shows some examples of these catalytic reactions. 

Gattermann aldehyde synthesis, 9, 2 Gattermann-Koch reaction, 5, 6 Germanes, addition to alkenes and alkynes, 13, 4 Glycals,... 

The reaction of alkenes (and alkynes) with synthesis gas (CO + H2) to produce aldehydes, catalyzed by a number of transition metal complexes, is most often referred to as a hydroformylation reaction or the oxo process. The discovery was made using a cobalt catalyst, and although rhodium-based catalysts have received increased attention because of their increased selectivity under mild reaction conditions, cobalt is still the most used catalyst on an industrial basis. The most industrially important hydrocarbonylation reaction is the synthesis of n-butanal from propene (equation 3). Some of the butanal is hydrogenated to butanol, but most is converted to 2-ethylhexanol via aldol and hydrogenation sequences. 

Alkenyl, Alkynyl, Aryl and Related Acids. Vinylphosphonates are an important group of compounds that have found use in organic transformations. They are also useful reagents for the synthesis of biologically active systems. The synthesis of vinylphosphonates is varied. However additional convenient routes to them are always welcome. Four recent reports demonstrated that zirco-nacycles (180), readily available from diethyl 1-alkynylphosphonates, are very useful precursors of different vinylphosphonates. They react with alkynes, aldehydes, ketones acyl chlorides and nitriles to produce, in a highly stereo- and regio-selective manner, substituted vinylphosphonates (181), (182), (183) (184) and (185) respectively (Scheme 46). 

Roth, G. J., Liepold, B., Mueller, S. G., Bestmann, H. J. Further improvements of the synthesis of alkynes from aldehydes. Synthesis 2004, 59-62. 

Most unsaturated substances such as alkenes, alkynes, aldehydes, acrylonitrile, epoxides, isocyanates, etc., can be converted into polymeric materials of some sort—either very high polymers, or low-molecular-weight polymers, or oligomers such as linear or cyclic dimers, trimers, etc. In addition, copolymerization of several components, e.g., styrene-butadiene-dicyclo-pentadiene, is very important in the synthesis of rubbers. Not all such polymerizations, of course, require transition-metal catalysts and we consider here only a few examples that do. The most important is Ziegler-Natta polymerization of ethylene and propene. 

Alkynic aldehydes likewise undergo intramolecular coupling to generate five- and six-membered ring carbocycles. This protocol has been utilized as a key step in the synthesis of isocarbacyclin (eq TA) Sml2 was found to be superior to several other reagents in this conversion. 

Rhodium complexes provide some of the most attractive catalysts for carbon manipulation with high reactivity, regioselectivity, scope, and functional group tolerance. In particular, rhodium complexes have displayed potential for the synthesis of various heterocyclic and carbocyclic compounds through the C—H bond activation reactions. Rhodium complexes have been shown to catalyze sp C—H bond insertion into several pi bonds including alkenes, alkynes, aldehydes, and imines. ... 

Multicomponent polymerization of alkynes, including tandem polymerization, provides an efficient approach for the synthesis of functional polymer materials with unique structures that are difficult to obtain using other synthetic methods. The MCPs based on alkyne monomers are still quite limited. Three types of reported MCPs of alkynes are reviewed MCPs of alkynes, aldehydes, and amines MCPs of alkynes, azides, and amines/alcohols and tandem polymerization of alkynes, carbonyl chloride, and thiols. These MCPs have overcome the limitations of MCPs such as strict stoichiometric balance, poor polymer solubility, and low M , of the products. This field is still in its infant stage and more comprehensive work is an urgent demand. Through such pioneering work, we hope to inspire research enthusiasm and accelerate the pace of development of efficient polymerizatiOTi approaches for synthesis of various polymer structures, and pave the way to novel functional polymer materials. 

These compounds are sources of the nucleophilic anion RC=C and their reaction with primary alkyl halides provides an effective synthesis of alkynes (Section 9 6) The nucleophilicity of acetylide anions is also evident m their reactions with aldehydes and ketones which are entirely analogous to those of Grignard and organolithium reagents... 

Sulfitation and Bisulfitation of Unsaturated Hydrocarbons. Sulfites and bisulfites react with compounds such as olefins, epoxides, aldehydes, ketones, alkynes, a2iridines, and episulftdes to give aHphatic sulfonates or hydroxysulfonates. These compounds can be used as intermediates in the synthesis of a variety of organic compounds. 

The synthesis of 10 features the SN2 displacement of the allylic acetate with migration of R2 from the ate complex6. Precursors 9 are prepared by the hydroboration of 3-acetoxy-l-alkynes that are available with very high enantiomeric purity via the asymmetric reduction of the corresponding l-alkyn-3-ones, and a substantial degree of asymmetric induction occurs in the conversion of 9 to 10. Best results, based on the enantioselectivity of reactions of 10 with aldehydes, are obtained when R2 is a bulky group such as isopinocampheyl (79 85 % ee)6. The yields of reactions of 10 with aldehydes are 62-76%. 

The cycloaddition of alkynes with the tributylphosphine-carbondisulfide adduct 131 results in the in situ formation of the ylides 132 which react with aldehydes to give the novel 2-arylidene or 2-alkylidene-l,3-dithioles 133 (Scheme 36) [132]. Concerning ylides C-substituted by sulfur we can also mention a publication on the behavior of various keto-stabilized ylides towards acyclic and cyclic a s-disulfides allowing the synthesis of substituted thiazoles, thiols, and dithiols [133]. 

Scheme 19 Synthesis of quinolines by iron(III)-catalyzed three-component coupling/hydroaryla-tion of aldehydes, alkynes, and amines...

The hydrosi(ly)lations of alkenes and alkynes are very important catalytic processes for the synthesis of alkyl- and alkenyl-silanes, respectively, which can be further transformed into aldehydes, ketones or alcohols by estabhshed stoichiometric organic transformations, or used as nucleophiles in cross-coupling reactions. Hydrosilylation is also used for the derivatisation of Si containing polymers. The drawbacks of the most widespread hydrosilylation catalysts [the Speier s system, H PtCl/PrOH, and Karstedt s complex [Pt2(divinyl-disiloxane)3] include the formation of side-products, in addition to the desired anh-Markovnikov Si-H addition product. In the hydrosilylation of alkynes, formation of di-silanes (by competing further reaction of the product alkenyl-silane) and of geometrical isomers (a-isomer from the Markovnikov addition and Z-p and -P from the anh-Markovnikov addition. Scheme 2.6) are also possible. 

In 2002, Braga el al. employed a chiral C2-symmetric oxazolidine disulfide as a ligand for the enantioselective synthesis of propargylic alcohols by direct addition of alkynes to aldehydes (Scheme 3.64). Good yields but moderate enantioselectivities (<58% ee) were obtained for the enantioselective alkyny-lation of aldehydes in the presence of ZnEt2. 

There are several procedures for synthesis of terminal alkenyl stannanes that involve addition to aldehydes. A well-established three-step sequence culminates in a radical addition to a terminal alkyne.150... 

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