Unsaturated carboxylic acid derivative

Chlorotrifluoroethylene was converted in one step using nBuLi to dieth-ylfluoromalonate, which was a useful precursor for 5-fluorouracil (84CL1573). Fluorinated pyrimidinones can also be obtained from a,fi-unsaturated carboxylic acid derivatives prepared from 1-phosphonyloxy-perfluoroalkyl-l-alkenephosphonates (86TL2879). 

The l-chloro-2,2-dibromocyclopropanes 164 similarly undergo the nickel-carbonyl-induced ring-opening carbonylation with an amine or an alcohol to give the / ,y-unsaturated carboxylic acid derivatives 165 and the dicarboxylic acid ones 166 [84]. The mechanism described above appears to be operating this is supported by the four-component condensation to 167. (Scheme 61 and 62)... 

Like unsaturated ketones, a,0-unsaturated carboxylic acid derivatives, e.g. lactones and anhydrides, undergo cycloadditions to alkenes. As for the preparative conditions (direct irradiation or sensitized experiments) these compounds are situated somewhere in between enones on the one side and olefins on the other. 

Attack on Unsaturated Carbon. The annual addition of phosphites to every variety of activated double bond continues. These include nitro-alkenes,9 a/S-unsaturated carboxylic acid derivatives,10 maleimides,11 fulvenes,12 and pyridinium salts.13 The reaction of diethyl phosphite with keten 0,N-, S,N, and Al,AT-acetals has been used to prepare the enamine phosphonates (19).14... 

Scheme 3.39. Reactions between a-aminoalkylcuprates and a,fl-unsaturated carboxylic acid derivatives [161].

Carboxylic acids and their derivatives like esters, amides, anhydrides, and acyl halides are formally synthesized from olefins, carbon monoxide, and compounds represented by Nu-H such as H2O, ROH, RNH2, RCOOH (Equations (4) and (5)). Alkynes also react under similar conditions to afford the corresponding unsaturated carboxylic acid derivatives. These reactions have been named hydrocarboxylation, hydroalkoxycarbonylation, and hydroaminocarbonylation. 

Table 2.1.5.3 Asymmetric hydrogenation of a, P-unsaturated carboxylic acid derivatives.

By Reaction with a./i-Unsaturated Carboxylic Acid Derivatives.117... 

By Reaction with (x,P-Unsaturated Carboxylic Acid Derivatives... 

A practicable strategy to provide access to chiral pyrazolidine-3-carboxylic acid (16) makes use of asymmetric dipolar cycloaddition of diazoalkanes to u,p-unsaturated carboxylic acid derivatives. For this purpose a chiral auxiliary of the alkene component is used, e.g. Op-polzer s1166 1671 (lf )-2,10-camphorsultam.t164l As shown in Scheme 7, by reaction of (tri-methylsilyl)diazomethane (41) with /V-( aery I oy I )cam p h ors u 11 am (42), the AL(4,5-dihy-dropyrazoline-5-carbonyl)camphorsultam (43) is obtained. Reduction of 44 with sodium cyanoborohydride leads to A-(pyrazolidine-3-carbonyl)camphorsultam (45) as the 35-dia-stereoisomer (ee 9 1) in 65 to 80% yields.[164] The camphorsultam 45 is then converted into the methyl ester 46 by reaction with magnesium methylate without racemizationj1641... 

The insertion of CO into 7r-allylpalladium complexes has been used to prepare various P/y-unsaturated carboxylic acid derivatives. The process can be initiated from preformed allyl complexes,227-235 catalyti-cally from appropriate ir-allyl precursors228,229 236 237 or from diene-Pd complexes.238 239 Particularly mild conditions, involving low pressures and temperatures, to accomplish this insertion have been discovered.235 The key reagent in allowing these mild conditions to be employed was found to be carboxy-late anions.235 For unsymmetrical allyl complexes, CO insertion occurs preferentially at the less-substituted allyl terminus (equations 71-73). 

Aldol condensationsPhase-transfer condensation of aldehydes with ,/ -unsaturated carboxylic acid derivatives is possible with anhydrous K2COj as base and Aliquat 336 as catalyst. 

The asymmetric aziridination of a, P-unsaturated carboxylic acid derivatives is a direct route to optically active aza-cyclic a-amino acids, and this class of chiral aziridines can also be used as chiral building blocks for the preparation of other amino acids, P-lactams, and alkaloids. Prabhakar and coworkers carried out an asymmetric aziridination reaction of tert-butyl acrylate with O-pivaloyl-N-arylhydroxylamine 25 in the presence of cinchonine-derived chiral ammonium salt 2e under phase-transfer conditions, which furnished the corresponding chiral N-arylaziridine 26 with moderate enantioselectivity (Scheme 2.24) [46],... 

A direct synthetic route to 4//-7-hydroxybcnzo[ ]tellurin-4-ones 138 involves acid-promoted dehydration of the corresponding (Z)-unsaturated carboxylic acid derivatives 137 (Scheme 14) <19980M3588>. These precursors can be readily prepared by a metallation-telluration sequence. Previous attempts to prepare molecules of this type, particularly the telluroflavones (R = Ph), were unsuccessful due to the unexpected reactivity of the C-Te bond relative to the C-Se and C-S bonds. 

J-Photo cycloadd ito n of a,f -Unsaturated Carboxylic Acid Derivatives 189 6.4... 

I 2]-Photocycloadditon of a, 3-Unsaturated Carboxylic Acid Derivatives (Substrate Classes A4, A5, and A6)... 

Photocyc oadditon of a,f3-Unsaturated Carboxylic Acid Derivatives 199... 

Lactam-fused compounds 127 are obtained by the reaction of secondary 1,1-enediamines with a,/ -unsaturated carboxylic acid derivatives such as methyl acrylate,... 

Another site-selective reaction of 35 with a,/3-unsaturated carboxylic acid derivatives in the presence of a Lewis acid has been reported (Scheme 25) [35]. The intermediate 37 possesses two nucleophilic sites the zirconium alkyl and the enol ether moieties. Starting from 37, two competing pathways lead accordingly to cyclopropane (38, path a) and/or cyclobutane (39, path b) derivatives. The... 

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