2-Isopropenyl bromide

More recently, a tandem Heck/allylic substitution cascade was used as a route toward various lactams. The reaction of 631a,b with 2-isopropenyl bromide in the presence of Pd(OAc)2 and (o-tolyl)3P gave the Heck adduct 632 that reacted further with H-Pd-Br to give the 71-allylpalladium complex 633. Intramolecular attack of the amide anion on the 7i-allyl complex followed by reductive elimination of Pd(0) afforded 634a,b in 77 and 75% yield, respectively (03OL259). Other vinyl bromides were also examined and found to give substituted pyrrolidinones and piperidones in moderate to good yields (50-82%). 

SAMPLE SOLUTION (a) In the preparation of organolithium compounds from organic halides, lithium becomes bonded to the carbon that bore the halogen. Therefore, isopropenyllithium must arise from isopropenyl bromide. 

Reaction conditions depend on the reactants and usually involve acid or base catalysis. Examples of X include sulfate, acid sulfate, alkane- or arenesulfonate, chloride, bromide, hydroxyl, alkoxide, perchlorate, etc. RX can also be an alkyl orthoformate or alkyl carboxylate. The reaction of cycHc alkylating agents, eg, epoxides and a2iridines, with sodium or potassium salts of alkyl hydroperoxides also promotes formation of dialkyl peroxides (44,66). Olefinic alkylating agents include acycHc and cycHc olefinic hydrocarbons, vinyl and isopropenyl ethers, enamines, A[-vinylamides, vinyl sulfonates, divinyl sulfone, and a, P-unsaturated compounds, eg, methyl acrylate, mesityl oxide, acrylamide, and acrylonitrile (44,66). 

Bicycloannelation.3 The 2 -enolatC (1) of isophoronc reacts with phenyl vinyl sulfone in THF containing 4 equivalents of HMPT (essential) to give the bicycloannelation product 2 in 38% yield. The yield is considerably greater than that obtained from the same reaction using vinyltriphenylphosphonium bromide. Reaction of 1 with isopropenyl phenyl sulfone gives 3 in 21% yield. 

BICYCLOANNELATION Hexamethyl-phosphoric triamide. Isopropenyl-tri-phcnylphosphonium bromide. Phenyl vinyl sulfone. 

Piers and co-workers (44) have reported that the cuprous chloride catalyzed 1,4-addition of isopropenylmagnesium bromide to the bicyclic enones 127 (R=H or CH3) gave exclusively the bicyclic ketones 128 (R=H or CH3) with the isopropenyl group axially oriented. Interestingly, with their trans ft/B ring junction, these enones are essentially conformationally rigid and their reactivity is in accord with the predictions made on the basis of stereo-electronic effects. 

Tanaka K, Uchiyama F, Asada A, Furusawa Y, Inubushi Y (1983) Synthetic Studies on a Picrotoxane Sesquiterpene, Coriamyrtin. I. The Grignard Reaction of 5-(2-Methy 1-1,3-dioxo-2-cyclopentyl)methyl-2,5-//-furanone with Isopropenyl-magnesium Bromide and Stereochemistries of the Products. Chem Pharm Bull 31 1943... 

A general route to acid fluorides, chlorides, bromides and iodides is provided by the reaction of enol esters, such as isopropenyl esters, with the appropriate hydrogen halide (equation 18). Phthalic acid dichloride in the presence of chlorosulfonic acid has been proposed as a reagent for the conversion of carboxylic esters to acid chlorides in high yield, as is shown in equation (19) for the cleavage of the ethyl ester of chlorofluoroacetic acid. °... 

Iron(III)sulfate, 223-224 Isatin, 331 Isatoic acid, 331 Isoatlantolactone, 263, 264 Isobutenyl acetate, 153 Isobutyronitrile, 110 Isocyanates, 14-15 Isoflavones, 410 Isopavine, 217 Isopenams, 325 Isophorone, 197, 198 Isopinocampheylborane, 224 Isoprene epoxide, 4 Isopropenyl phenyl sulfone, 316 Isopropenyltriphenylphosphonium bromide, 225... 

A similar cyclization reaction proceeded on treatment of 2-haloethanal allyl acetal and allyl 2-halophenyl ether with Grignard reagents in the presence of an Fe(II) salt catalyst [177]. Addition of phenylmagnesium bromide to a solution of 2-iodoethanal prenyl acetal 176a in the presence of a catalytic amount of Fe(ll)Cl2 gave the isopropenyl-substituted tetrahydrofuran derivative 177 in 52% yield with an isopropyl-substituted product 180 (13%) (Scheme 3.164). 

Isopropenyl acetate, 191, 230, 309, 325 3-IsopropenylcycIohexanone, 92 Isopropenyllithium, 456 Isopropenylmagnesium bromide, 92 Isopropenyl methyl ether, 230-231 Isopropylamine, 44, 414 rw-4- 1 sopropylcyclohexane-1 -carboxylic acid, 412, 413... 

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