Penta-2,3-dienoate

Pyrrolo[l,2-a]azepin-5-one (11), prepared by cyclization of methyl 5-(pyrrol-2-yl)penta-2,4-dienoate (10) with sodium hydride in toluene, in trifluoroacetic acid solution forms the diatropic 5-hydroxypyrrolo[1,2-a]azepinium ion 12.216 6-Methyl-5//-pyrrolo[l,2-tf]azepin-5-one(mp41 -43 C), formed in low yield (20%) by the action of [(ethoxycarbonyl)methylene]triphenylphos-phorane on 4-(pyrrol-2-yl)but-3-en-2-one, behaves similarly. 

The next step in degradation involves hydrolysis of 2-hydroxy-6-keto-6-phenylhexa-2, 4-dienoate to benzoate and 2-hydroxy-penta-2,4-dienoate encoded by the hydrolase BphD. 

Reaction of thiobenzaldehyde-anthracene cycloadduct 385 with 2-methoxyfuran in toluene at 90 °C for 3 h gave thiirane 386 (mixture of (E)- and (Z)- isomers) and methyl 2-(Z)-penta-2,4-dienoate 387 (Equation 59) <2003TL1179>. 

FMO calculations using PM3-C1 were used to investigate the regioselectivities obtained by the photochemical reactions between 2-pyridone and penta-2,4-dienoate." The hard and soft acid-base principle has been successfully used to predict product formation in Patemo-Buchi reactions." The 2 - - 2-photo-cycloaddition of homobenz-valene with methyl phenylglyoxylate, benzyl, benzophenone, and 1,4-benzoquinone produced the corresponding Patemo-Biichi products." The photo-cycloaddition of acrylonitrile to 5-substituted adamantan-2-ones produces anti- and 5y -oxetanes in similar ratios irrespective of the nature of the 5-substituent." ... 

Aspinall, I H, Cowley, P M, Stoodley, R J, Enhanced discrimination by aza dienophiles over their olefinic counterparts for the diastereotopic faces of methyl ( , )-5-(2, 3. 4, 6 -tetra-0-acetyl-p-D-glucopyranosyloxy)penta-2,4-dienoate. Tetrahedron Lett., 35, 3397-3400, 1994. 

Methyl ( )-penta-2,4-dienoate, under analogous conditions, is converted into the cycloadduct methyl ( )-3-(3-methylenecyclopentyl)prop-2-enoate (5) in 25% yield. A cotrimer 6 containing two molecules of MCP is additionally formed. Remarkably, only the product resulting from cycloaddition involving the terminal double bond is formed. When the substrate is changed... 

Kuroda, C., Mitsumata, N., and Tang, C.Y., An acylative C-C single-bond cleavage and a selfcyclization of ethyl 2-(trinicthylsilylmethyl)penta-2.4-dienoate of its free acid under Ritter conditions. Bull. Chem. Soc. Jpn., 69, 1409, 1996. 

The 1-azadiene and the dienophilic character of 2-alkenyl-5,6-dihydro-4//-l,3,4-oxadiazines (150 Section 6.17.6.2) have been explored (Scheme 21) <93TL457>. Attempts to effect cycloaddition with DMAD, dimethyl fumarate, and acrylonitrile failed, whereas with maleic anhydride and A-methylmaleimide unexpected noncyclic adducts (e.g. 151) are obtained. The alkenyl oxadiazines also fail to give cycloadducts with l-methoxy-3-trimethylsilyloxy-l,3-butadiene with or without the presence of a Lewis acid catalyst. However, with methyl penta-2,4-dienoate mixtures of diastereo-isomeric products (e.g. 152) are formed, albeit slowly, by [4 + 2] cycloaddition at the alkenyl side chain, rather than at the C2—N3 imine bond. 

In the abscisic acid field, syntheses of 6 -monodemethylabscisic acid (144) and methyl 5-(r,6 -epoxy-2, 2 -dimethylcyclohexyl—3-methyl-(2Z,4B)-penta-2,4-dienoate (145) have been described, and the synthesis of some compounds that may be considered to be aromatic analogues of abscisic acid has also been reported. ... 

Dien-4-ynes 136 (R -R = alkyl) are produced from propargylic carbonates 135 and terminal alkynes in the presence of a palladium-phosphine complex and copper(I) iodide. The linear co-dimerization of terminal acetylenes and 1,3-dienes is catalyzed by ruthenium(cyclooctadiene)(cyclooctatriene)(trialkylphosphine) (alkyl = Et, Bu or octyl) thus 1-hexyne and methyl penta-2,4-dienoate give a mixture of the eneynes 137 and 138. Coupling of octa-l,7-diyne (139) with the acetylenic bromo acid 140 in aqueous THF-methanol containing butylamine, hydroxylamine hydrochloride and copper(I) chloride gave a mixture of the triynyl acids 141 and 142. ... 

A microwave-assisted thermolysis of methyl 4-(2-aUylphenoxy)penta-2,4-dienoates in toluene leads to a few dihydroxanthenes (13CEJ6566). A platinum(II) complex [(S)-(xylyl-phanephos)Ptl2] in combination with... 

Benzylamine added to a soln. of ethyl 2,3-dicarbethoxy-rran5-5-dimethylamino-penta-2,4-dienoate in abs. ethanol, and refluxed 5 hrs. l-benzyl-3,4-dicarbethoxy-2(lH)-pyridone. Y 90%. F. e. s. R. F. Borch et al., J. Org. Chem. 37, 1141 (1972). 

Olivetol-dy. The synthetic procedure of Pitt l. (6) was used with some modifications to increase the incorporation of deuterium. Methyl 5-(3,5-dimethoxyphenyl)penta-2,4-dienoate was reacted with LiAlDi+ followed by hydrogenation with D using the catalyst tris(triphenylphosphine)rhodium chloride. The 5-(3,5--dimethoxyphenyl)pentan-l-ol-l,1,2,3,4,5was then reacted with PBr3, LiAlDii, and BBr3 according to Pitt. (6) to yield... 

The enol-enol tautomerism of ethyl 2-benzoyl-5-(2-futyl)-3-hydro 9 -penta-2,4-dienoate and ethyl 2-acetyl-3-hydro3q -5-phenyl-penta-2,4-dienoate in different solvents has been studied by Michalik and co-workers with the aid of /ohc, 7ohc and t/njOH couplings and BP86/ TZVP DFT computations. It has been established by the authors that the... 

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