Carbon dioxide reactions with amides

The yield of product from the carbon dioxide reaction with the alkyne anion was very poor, as it was with the vinyl Grignard derived from 1.166. Extending the carbon chain between the triple bond and the dimethylamino group, as in the reaction of 1.170 with sodium amide and then carbon dioxide, - however, led to... 

A V -Carbonyldiimidazole (CDI) is prepared in a convenient and safe procedure from phosgene and imidazole as a non-toxic crystalline compound (m.p. 116-118 °C).[5],[6] It reacts almost quantitatively at room temperature or by short and moderate heating with an equimolar quantity of a carboxylic acid in tetrahydrofuran, chloroform, or similar inert solvents within a few minutes to give the corresponding carboxylic acid imidazolide, which is formed under release of carbon dioxide, together with one equivalent of readily separable and recyclable imidazole.Thus, this reaction leads under very mild conditions to the activation of a carboxylic acid appropriate for transacylation onto a nucleophile with an alcohol to an ester, with an amino compound to an amide or peptide, etc. 

BENZYLCARBONYL CHLORIDE (501-53-1) Combustible liquid (flash point 176°F/80°C oc). Vigorous decomposition occurs at these temperatures thus, these values are anomalous due to the effect of the decomposition products (benzyl chloride and carbon dioxide). Reacts with water, producing hydrochloric acid. Violent reaction with strong oxidizers, bases. Incompatible with strong acids, nitrates. The aqueous solution is incompatible with sulfuric acid, alkalis, ammonia, aliphatic amines, alkanolamines, alkylene oxides, amides, epichlorohydrin, organic anhydrides, isocyanates, nitromethane, vinyl acetate. Attacks metals in the presence of moisture. 

In all of the syntheses discussed, alkoxy derivatives of a-aminoaceto-phenone or of /3-phenethylamine were employed to supply the main structural outline of the isoquinoline system. Some of these amines are hard to obtain, especially if the resistant aromatic methoxyl groups are replaced by more sensitive substituents which may serve in the preparation of partly demethylated derivatives of papaverine or laudanosine. A significant innovation (60) which avoids the preparation of such unstable amines is the degradation of j3-phenylpropionic acid azides (hydrocinnamic acid azides) to the corresponding isocyanates, which add to the required phenylacetic acids probably with the intermediate formation of four-membered cyclic hemiacetals. The latter are transformed to A-carboxylic acids, which lose carbon dioxide and yield amides needed in the isoquinoline syntheses. In practice, the azide is heated with the phenylacetic acid in benzene solution for several hours, and the amide is isolated from the reaction mixture without difficulty. 

Carbon dioxide can also form carbamates by reaction with amides of non-metallic elements [78-84, 136-144]. Most examples reported in the literature deal with amides of silicon, germanium, and phosphorus. Among these, the insertion of the heterocumulene into the P-N bond of hexaalkylphosphorus triamides P(NR2)3, which affords phosphocarbamates species of formula P(NR2)3 (02CNR2) t, has received particular attention for its potential in chemical synthesis, because this reaction opens a route to the phosgeneless synthesis of carbamate esters [138,139] and ureas [140]. 

The reaction commences at about 120° the carbamic acid formed decomposes immediately into carbon dioxide and ammonia. The latter may form the ammonium salt with unreacted acid the ammonium salt also reacts with urea at temperatures above 120° to yield the amide ... 

Carboxyhc acids react with aryl isocyanates, at elevated temperatures to yield anhydrides. The anhydrides subsequently evolve carbon dioxide to yield amines at elevated temperatures (70—72). The aromatic amines are further converted into amides by reaction with excess anhydride. Ortho diacids, such as phthahc acid [88-99-3J, react with aryl isocyanates to yield the corresponding A/-aryl phthalimides (73). Reactions with carboxyhc acids are irreversible and commercially used to prepare polyamides and polyimides, two classes of high performance polymers for high temperature appHcations where chemical resistance is important. Base catalysis is recommended to reduce the formation of substituted urea by-products (74). 

To a solution of 516 nig (1 mmol) of the stannane 17 (R = C.H3, 95% ee) in 10 ml of dry DME is added, at — 78 C, 0.62 nlL of 1.6 M BuLi (1 mmol) in hexane. After 5 min gaseous carbon dioxide is bubbled into ihe yellow solution. The reaction mixture decolorizes immediately. After a further 10 min the reaction is quenched with sat. aq NH4C1. The organic layer is extracted with 2N aq NaOll. Acidification of the aqueous layer with 2N aq IICI is followed by extraction with F.t,o, drying over Na,SC)4 and concentration in vacuo yield 193 mg (92%) 95% ec [determined by HPLC-analysis of the amide obtained by derivati/alion with (S)-x-phenylelhylaminc] [a]20 — 37 (r = 1,6, CI1C1,). 

Diisocyanates are highly reactive and readily available compounds. The diisocyanates and acids form amides with the liberation of carbon dioxide side reactions are possible as diisocyanates can also react with an amide group. 

Isocyanates react with carboxylic acids to form amides, ureas, anhydrides, and carbon dioxide, depending on reaction conditions and the structure of the starting materials (Scheme 4.13). Aliphatic isocyanates more readily give amides. Aromatic isocyanates tend to react with carboxylic acids to first generate anhydrides and ureas, which at elevated temperatures (ca. 160°C) may further react to give amides. In practice, the isocyanate reaction with carboxylic acid is rarely utilized deliberately but can be an unwanted side reaction resulting from residual C02H functionality in polyester polyols. 

Zinc carbamate complexes are well known, and the structural types and stabilities can be compared with thiocarbamates and dithiocarbamates which are discussed in Sections 6.8.11.1.3 and 6.8.7.1.4482 Carbamates of zinc can be formed from the reaction of carbon dioxide with alkylzinc alkyl amides and further reaction with alkylzinc can give a distorted cubane structure.483 The tetrameric diethylcarbamate species initially formed can also be used to produce monomeric or dimeric carbamate structures in reaction with amines tetramethylethylenediamine forms a monomer [(Me2NCH2)2Zn(02CN(C2H5)2)2] with an octahedral zinc center and pyridine forms a dimer[CsH5NZn2Me(02CN(C2H5)2)3] with tetrahedral zinc centers.484... 

Allenamide ( )-13 was prepared by trapping the corresponding lithioallene with carbon dioxide, followed by conversion of the carboxylate to the amide. Chromatographic resolution of the enantiomers of 13 was easily accomplished on a 10x250mm Chiralcel OD HPLC column. Addition of vinyllithium 14 to (+)-13, followed by quenching the reaction with aqueous NaH2P04, led to cyclopentenone (—)-15 in 64% yield with >95% chirality transfer (Eq. 13.4). The absolute stereochemistry of (-)-5 is consistent with the mechanistic hypothesis put forth in Eq. 13.3 [8]. 

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