Carbonyl bromide chloride synthesis

Even the sterically hindered 2,6-disubstituted aryl iodide 443 is carbonylated smoothly to give 445. Alkyl iodide present in the alcoholic component 444 remains intact under the carbonylation conditions. This carbonylation reaction is a key reaction in the synthesis of zearalenone (446) [216]. Optimal conditions for technical synthesis of the anthranilic acid derivative 448 from bromide 447 has been studied, and it has been found that A-acetyl protection of 447, which has a chelating effect, is important [217]. Cheaply available chlorides are rather inert [13]. The carbonylation of chloride 449 in the presence of DBU and Nal gives the amide 450 [218],... 

Allylic bromides can also serve as progenitors for nucleophilic organochromium reagents. An elegant example is found in Still and Mobilio s synthesis of the 14-membered cembranoid asperdiol (4) (see Scheme 2).7 In the key step, reduction of the carbon-bromine bond in 2 with chromium(n) chloride in THF is attended by intramolecular carbonyl addition, affording a 4 1 mixture of cembranoid diastereoisomers in favor of the desired isomer 3. Reductive cleav-... 

The Aggarwal group has used chiral sulfide 7, derived from camphorsulfonyl chloride, in asymmetric epoxidation [4]. Firstly, they prefonned the salt 8 from either the bromide or the alcohol, and then formed the ylide in the presence of a range of carbonyl compounds. This process proved effective for the synthesis of aryl-aryl, aryl-heteroaryl, aryl-alkyl, and aryl-vinyl epoxides (Table 1.2, Entries 1-5). 

This microwave-accelerated double alkylation reaction was applicable to a variety of aniline derivatives and dihalides, furnishing N-aryl azacycloalkanes in good to excellent yields [89]. The reaction was applicable to alkyl chlorides, bromides and iodides and was extended to include hydrazines [90]. This improved synthetic methodology provided a simple and straightforward one-pot approach to the synthesis of a variety of heterocycles such as substituted azetidines, pyrrolidines, piperidines, azepanes, N-substituted-2,3-dihydro-Iff-isoindoles, 4,5-dihydro-pyrazoles, pyrazolidines, and 1,2-dihydro-phthalazines [91]. The mild reaction conditions tolerated a variety of functional groups such as hydroxyls, carbonyls, and esters. 

Vinyllithiums of type 663 (R2 = R3 = H) reacted with primary alkyl bromides, carbonyl compounds, carbon dioxide, DMF, silyl chlorides, stannyl chlorides, disulfides and phenylselenyl bromide142,970-979. Scheme 173 shows the synthesis of dihydrojasmone 669 from the corresponding 1,4-diketone. a-(Phenylsulfanyl)vinyllithium 665, prepared from phenyl vinyl thioether, reacted with hexanal and the corresponding adduct 666 was transformed into its acetoacetate. This ester 667 underwent a Carrol reaction to produce the ketone 668, which was transformed into the cyclopentenone 669 by deprotection either... 

Numerous aryl bromides, iodides [203], borates [204] and triflates [205, 206] have been successfully carbonylated. Triflates could serve as a route for the synthesis of arenecarboxylic acid derivatives from phenols. This carbonylation using dppf in a catalytic mixture generally shows higher efficiency than PPhj or P(o-Tol)3 [207]. Poor performance is also noted for PPhj in a Pd-catalyzed vinyl substitution of aryl bromides [208]. Side-reactions involving the formation of [PPhjAr]Br and ArH are responsible. A system which is catalyzed effectively by PdCljfdppf) under 10 atm CO is the desulfonylation of 1-naphthalenesulfonyl chloride 58 in the presence of Ti(OiPr)4. Formation of isopropyl 1-naphthoate 59 can be explained in a sequence of oxidative addition, SOj extrusion, carbonylation and reductive elimination (Fig. 1-27) [209]. A notable side-product is di-l-naphthyl disulfide. 

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