Alkyne/ester coupling

The reaction was applied to the formation of arylcopper used for homocoupling and coupling reactions, which have already been described in Section IV.B.2. In addition, it was established that the simple use of copper(I) salts in polar solvents permitted the transmetallation from tin to copper. The transient vinylcopper reagent was subjected to various intramolecular reactions such as coupling with vinyl halides , addition to a, /S-unsaturated ketones , to a, /3-unsaturated esters and addition to a, /3-alkynic esters . In addition to copper(I) halides, the reaction can be mediated by copper(I) cyanide and... 

An alkyne/5-hydroxy-2-pentynoic ester coupling leads to dihydropyran derivatives. Formation of the homologous heterocycle from ethyl 6-hydroxy-2-hexynoate proceeds in two stages, the second stage is promoted by Pd(OCOCF3)2. ... 

Alkynic esters are prepared by the coupling of terminal alkynes with chlorofor-mate 157. Butyl chloroformate (157) is an unstable compound, and the reaction... 

Surprisingly, methyl esters are also suitable substrates whereby intramolecular cyclization occurs with concomitant loss of methyl iodide. Larock used internal alkynes as coupling partners for lactone synthesis (Scheme 2.33) [74]. The proposed mechanism involves oxidative addition of Pd(0) to the aryl iodide, followed by addition across the alkyne and cyclization of the carbonyl O of the ester to form an oxonium ion. Reductive elimination followed by loss of the methyl group then yields the product [74]. Shen and coworkers also reported a variant utilizing o-2,2-dibromovinylbenzoates (Scheme 2.34) [79]. 

The cross-coupling of unactivated alkyl bromides and iodides with aryl(trimethoxy)silanes can be accomplished with PdBr2-P(f-Bu)2Me or air stable [HP(i-Bu)2Me]BF4-TBAF. Notably, the reactions occur under ambient conditions and with an array of compatible functional groups on the electrophile including ethers, acetals, nitriles, alkynes, esters, amides, and ketones (eq 41). Electron-rich and electron-deficient aryl(trimethoxy)silanes can be employed with the former providing higher yields. 

The fully intermolecular variant of this concept has also been realized. A variety of propiolates were coupled with allenes to afford a regioselective aromatic cycloadduct (Scheme 2.12) [9]. A symmetric ester bearing an alkyne was coupled successfully with butyl allene to afford arene 46 in high yields. Unsymmetrical internal alkynes (i.e., methyl- and phenyl-substituted propiolates) were also coupled with butyl-, cyclohexyl-, and phenyl-substituted allenes in high yields (47 to 50, Scheme 2.12). The current scope of the reaction is confined to the use of activated alkyne substrates in this cycloaddition. 

Post-polymerization modification of reactive polymer films provides the possibility to design complex coatings associated with intricate structure and morphology [1, 4, 97, 98]. Using a simple procedure, two or more types of chemical functionalities can be applied onto substrates that are contained in covalently grafted polymer films. Multifunctional surfaces can be fabricated by sequential click reactions or simultaneous multiple click reactions in one-pot. Click-like reactions such as thiol-based additions, activated ester coupling, and azide-alkyne cycloadditions are those most used for post-polymerization modification, because these reactions yield orthogonal reactive polymer brushes rapidly and quantitatively [17]. 

Catalytic intermolecular coupling of alkene and alkyne is quite a challenging task. Nevertheless, cyclopentadienyl rutheniumcomplexes are able to catalyze alkyne-alkene coupling (an Alder-ene type reaction) to a mixture of the re-gioisomeric products 120 and 121 (Scheme 52). The most efficient catalysts are the complexes 78 or 53. The latter is more reactive. The scope of the reaction with respect to substituents attached to the both reactants is enormous ester, hydroxy, nitrile, ether, amino, and arylhalide groups are tolerated. Both terminal and internal alkynes and alkenes can be used. Some typical examples are summarized in Table 24 [67,69]. 

In the coupling of the allenyl ester 7 with a terminal alkyne, an electron-deficient phosphine (Ph3P) gave the enyne-conjugated ester 8 as the major product, while an electron-rich phosphine (TDMPP or TTMPP) yielded the non-conjugated enyne esters ( )- and (Z)-9[4],... 

Ihmels H, Otto D (2005) Intercalation of Organic Dye Molecules into Double-Stranded DNA - General Principles and Recent Developments. 258 161-204 Iida H, Krische MJ (2007) Catalytic Reductive Coupling of Alkenes and Alkynes to Carbonyl Compounds and Imines Mediated by Hydrogen. 279 77-104 Imai H (2007) Self-Organized Formation of Hierarchical Structures. 270 43-72 Indelli MT, see Chiorboli C (2005) 257 63-102 Inoue Y, see Borovkov VV (2006) 265 89-146 Ishii A, Nakayama J (2005) Carbodithioic Acid Esters. 251 181-225 Ishii A, Nakayama J (2005) Carboselenothioic and Carbodiselenoic Acid Derivatives and Related Compounds. 251 227-246... 

---