Ethyl propiolate complex

No relevant iridium alkynyls exist to date. However, the rhodium complexes Tp RhH(C = CPh)(PR3) (R = C6H5 (559), C6H4F-4 (560)) have been prepared by the addition of phenylacetylene to the respective bis(phosphine) complexes, and the ethyl propiolate complex Tp RhH(C = CC02Et)(PPh3) (561) has very recently been prepared in the same way. ... 

The effect of stoichiometry, substituent, and temperature were investigated in reactions between the hydride HCo(tdppep) (19) and a number of alkynes.175 The cr-acetylide complex (20) and the (7-alkenyl (21) are formed from the stoichiometric reaction with ethyl propiolate. However, when a ten-fold excess of ethyl propiolate is used, the acetylide complex is formed quantitatively and one equivalent of alkyne is hydrogenated to alkene. Forcing conditions and a large excess of... 

CH3(CH2)4CH = CHCH = CHC00CH2CH3, C12H20O2, Mr 196.29, bp6i> 70-72 °C, has been identified in pears and has the typical aroma of Williams pears. Synthesis of ethyl 2-trans-4-cw-decadienoate starts from cis-l-heptenyl bromide, which is converted into a 1-heptenyllithium cuprate complex with lithium and copper iodide. Reaction with ethyl propiolate yields a mixture of 95% ethyl 2-trans-A-cis- and 5% ethyl 2-tranx-4-tranx-decadienoate. Pure ethyl 2-trans-A-cis-decadienoate is obtained by fractional distillation [25]. A biotechnological process for its preparation has been developed [26]. 

Trost exploited the annulation of electron rich phenols and alkynoates to obtain coumarins in the presence of transition metal complexes. Ethyl propiolate and 3,4,5-trimethoxyphenol were coupled in formic acid in the presence of a palladium complex and sodium acetate to give 5,6,7-trimethoxycoumarin via a net C-H insertion in acceptable yield (4.42.). The coupling, characteristic of electron rich phenols, was also catalyzed by other transition metals, such as platinum or silver.56... 

Ethyl propiolate or DMAD and the quinazoline imine (452) give a complex mixture.431... 

Scheme 9 Preparation of the imprinted polymer for the catalysis of 1,3-dipolar cycloaddition between azides and alkynes obtained using the ethyl propiolate (52) and the azide (53) to generate the imprinted imprinting complex (54)...

The tetrahydropyran-based iron complex 524 can undergo demetallation followed by a cycloaddition reaction with ethyl propiolate to afford a regioisomeric mixture of polysubstituted chromans (Scheme 116) <2001TL6987>. 

The ate-complexes (34) also react with benzylic halides aroyl chlorides allyl halides and proj r l halides to afford the (x>rr ponding products, respectively (Eq. 75). (E)-a,P-Unsaturated carboxylic esters can also be obtains by the reaction of such borate complexes with ethyl propiolate The same type of reaction between copper(I) methyltrialkylborates and l-(l-pyrrolidinyl)-6-chloro--1-cyclohexene gives the corresponding alkylation products which are readily hydrolyzed to 2-alkylcyclohexanone... 

The kinetic hydrogen isotope effects which have been observed in the hydrogen-ene reactions of deuterium-labelled alkenes with singlet oxygen, tV-pheny I triazolincdione, nitrosopentafluorobenzene, formaldehyde, methyl chloroacrylate, and ethyl propiolate as the enophiles, and the stereoselectivity of the reactions, imply the initial formation of a complex between the alkene group and the enophile. The various products which have been identified in the metalloene reactions can be rationalised on die basis of a similar mechanism (Scheme 9-2).67... 

The tungsten carbene complex 408 reacts with phenylacetylene to give the phenol 409, accompanied by the methanol trapping product 410 and the cyclobutenone 41 Cycloaddition of 1,1-dimethylallene to ethyl propiolate affords the cyclobutene 412. ... 

The action of the complex 570 on various alkynes gives diverse products ethyl propiolate affords a mixture of all three possible triethyl benzenetricarboxylates, phenylacetylene yields mainly the trans-QnyviQ 571 3-hexyne behaves similarly, but 1-octyne isomerizes to 2-octyne . The palladacyclopentadiene 572 catalyses the co-trimerization of hex-3-yne... 

How to control the regioselectivity of the PKR is another topic of fundamental and practical importance. For a long time, it was supposed that the steric effects of the acetylenic substituents are mainly responsible for the observed regioselectivity [140]. In the intermolecular PK reaction with the larger acetylenic substituent, olefin coordinates adjacently to the less bulky acetylenic substituent and that the subsequent C-C bond formation occurs between an olefinic carbon and this closer acetylenic carbon eventually leading to the a-substituted cyclopentenone. Indeed, ethyl propiolate under PK conditions yields mainly an a-carbethoxy-substituted cyclopentenone [143]. However, ethyl butynoate under similar conditions reacts to form only a S-carbethoxy-substituted derivative ([144] for other reactions with 2-aUcynoates, see [145]). To rationalize this, a detailed DFT B3LYP study has been carried out by Robert et al. [140] in 2001 on alkynedicobalt hexacarbonyl complexes (33 in Scheme 23) to probe for the first time whether electronic... 

Acetylenes having a terminal hydrogen sometimes add the acetylenic carbon-hydrogen bond across the planar d complex to form a hexa-coordinate hydridoacetylide complex 31). The only well-studied example is the reaction of ethyl propiolate with the iridium complex (XI) to form (XXVII). 

Reaction of arenes Ar-H with 2equiv of ethyl propiolate HC=CC02Et can be catalysed by Pd(II) or Pt(II) complexes with bidentate ligands dppe or dppm in the presence of CF3CO2H to afford arylbutadiene derivatives (2E,4Z)-ArCH=C(C02Et)CCH=CHC02Et. The reaction is believed to commence with an unft-addition of the arene and the metal to the propiolate C=C bond, followed by a yn-addition to another propiolate molecule. ... 

Yamashita, A. and Scahill, T.A. (1982) Reaction of aryl chromium carbene complexes with ethyl propiolate. A versatile vinyl ether formation. Tetrahedron Letters, 23, 3765-3768. 

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