And double carbonylation

The alkylurea 576 and oxamide 577 are formed by oxidative carbonylation of amines under CO pressure using Pd/C as a catalyst[518]. The urea formation proceeds under atmospheric pressure using PdCh and CuCl2[519]. The mono-and double carbonylations of / -aminoethanol (578 and 579) afford the cyclic carbamate (oxazolidinones) 580 and oxamide (morpholinediones) 581 [520,521]. 

Mono- and double carbonylation of phenetyl bromide with cobalt-phosphine catalysts afforded benzylacetic (Baa) and benzylpymvic (Bpa) acids respectively [23] (Scheme 5.5). The highest yield of benzylpymvic acid (75 %) was obtained with [Co2(CO)8], while addition of the water soluble phosphines TPPMS or TPPTS decreased both the yield of carbonylated products and the selectivity to Bpa. 

The carbonylation of C-X derivatives represents a large family of related homogeneous metal-catalyzed organic reactions (eq. (1)). Prominent members include hydroxy, alkoxy, and amido carbonylations, and double carbonylations. 

Reductive carbonylations of aryl halides to benzaldehydes, amidocarbonylations, and double carbonylations of C—X bonds are of interest in industry. 

The oxidative carbonylation and double carbonylation of amines is catalyzed by PdCl2/CuCl2 in the presence of acid and Bu OOBu as oxidizing agent at room temperature see equation (58). Bulky amines give good yields of double-carbonyla-tion products.In a related system, piperidine is doubly carbonylated to ox-amates in the presence of a [PdCl2(MeCN)2]/CuI catalyst, O2 as the oxidant and... 

Carbonylation in the presence of secondary amines provides either amides or a-keto amides by single and double carbonylations. Also, the corresponding a-keto esters are prepared. It was reported that ratios of single and double carbonylations depend mainly on the nature of the phosphine ligands. It was claimed that PMePh2 or DPPB is a suitable ligand for double carbonylation [16]. 

With respect to carbonylations, reductive carbonylations of aryl hahdes to benzaldehy-amidocarbonylationsf °° of in situ produced a-haloamides to yield Af-acylamino acids, and double carbonylations of C—bonds are of interest to industry. 

One extra disconnection is all we need to cope with misaturated heterocycles. If a nitrogen atom is joined to a double bond in a ring, we have a cyclic enamine. This is made from an amine and a carbonyl compound in the same way as ordinary enamines ... 

The o-keto ester 513 is formed from a bulky secondary alcohol using tricy-clohexylphosphine or triarylphosphine, but the selectivity is low[367-369]. Alkenyl bromides are less reactive than aryl halides for double carbonyla-tion[367], a-Keto amides are obtained from aryl and alkenyl bromides, but a-keto esters are not obtained by their carbonylation in alcohol[370]. A mechanism for the double carbonylation was proposed[371,372],... 

Endo adducts are usually favored by iateractions between the double bonds of the diene and the carbonyl groups of the dienophile. As was mentioned ia the section on alkylation, the reaction of pyrrole compounds and maleic anhydride results ia a substitution at the 2-position of the pyrrole ring (34,44). Thiophene [110-02-1] forms a cycloaddition adduct with maleic anhydride but only under severe pressures and around 100°C (45). Addition of electron-withdrawiag substituents about the double bond of maleic anhydride increases rates of cycloaddition. Both a-(carbomethoxy)maleic anhydride [69327-00-0] and a-(phenylsulfonyl) maleic anhydride [120789-76-6] react with 1,3-dienes, styrenes, and vinyl ethers much faster than tetracyanoethylene [670-54-2] (46). 

Reactions of the Side Chain. Benzyl chloride is hydrolyzed slowly by boiling water and more rapidly at elevated temperature and pressure in the presence of alkaHes (11). Reaction with aqueous sodium cyanide, preferably in the presence of a quaternary ammonium chloride, produces phenylacetonitrile [140-29-4] in high yield (12). The presence of a lower molecular-weight alcohol gives faster rates and higher yields. In the presence of suitable catalysts benzyl chloride reacts with carbon monoxide to produce phenylacetic acid [103-82-2] (13—15). With different catalyst systems in the presence of calcium hydroxide, double carbonylation to phenylpymvic acid [156-06-9] occurs (16). Benzyl esters are formed by heating benzyl chloride with the sodium salts of acids benzyl ethers by reaction with sodium alkoxides. The ease of ether formation is improved by the use of phase-transfer catalysts (17) (see Catalysis, phase-thansfer). 

Two double bonds. This is the most important class which includes the aromatic compounds pyrazole (3), indazole (4) and isoindazole (5), their non-aromatic isomers, pyrazolenines (or 3iL-pyrazoles 6), isopyrazoles (or 4JT-pyrazoles 7) and 3JT-indazoles (8), and the carbonyl derivatives of pyrazolines with the endocyclic double bond in positions 1, 2 or 3, i.e. (9), (10) and (11), respectively. The indazolones (12) and the pyrazolidinediones (13) and (14) also belong to this group. 

One double bond. The three pyrazolines, A - (15), A - (16) and A -pyrazoline (17), and the carbonyl derivatives of pyrazolidines like (18), are the most representative compounds of this group. 

Ozone cracking is a physicochemical phenomenon. Ozone attack on olefinic double bonds causes chain scission and the formation of decomposition products. The first step in the reaction is the formation of a relatively unstable primary ozonide, which cleaves to an aldehyde or ketone and a carbonyl. Subsequent recombination of the aldehyde and the carbonyl groups produces a second ozonide [58]. Cross-linking products may also be formed, especially with rubbers containing disubstituted carbon-carbon double bonds (e.g. butyl rubber, styrene-butadiene rubber), due to the attack of the carbonyl groups (produced by cleavage of primary ozonides) on the rubber carbon-carbon double bonds. 

The results of the reductions of some steroidal a,)3-unsaturated ketones have been summarized by Brown. " The carbonyl group is usually reduced to the hydrocarbon, but the behavior of the double bond depends on the structure of the compound undergoing the reduction. Cholest-4-en-3-one gives chol-est-4-ene. Addition of aluminum chloride to a solution of a 4-ene-3,6-dione followed by treatment with LiAIH4 gives the 4-ene-6-one. Steroid 4,6-dien-3-ones yield mixtures of dienes. When the ketone and double bond are in different rings the results become even more complex dienes as well as mono-enes are obtained. 

Strategy In the aldol reaction, H2O is eliminated and a double bond is formed by removing hvo hydrogens from the acidic a position of one partner and the carbonyl oxygen from the second partner. The product is thus an a,/3-unsaturated aldehyde or ketone. 

Stereocontrol in the formation of spiroketals has been achieved in the alkylation of 2-(benzenesulfonyl)pyrans with allylsilanes <96JOC7860> and using a double carbonyl cycUsation strategy <96SL1065>. Spirocyclisation of protected dihydroxydiketones yields cis- and trans- l,7,9-trioxadispiro[5.1.5.3]hexadecanes the latter isomer is the thermodynamically more stable <96TL5461>. 

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