Allyl chloride 4 + 3 cycloaddition reactions

The first, and so far only, metal-catalyzed asymmetric 1,3-dipolar cycloaddition reaction of nitrile oxides with alkenes was reported by Ukaji et al. [76, 77]. Upon treatment of allyl alcohol 45 with diethylzinc and (l ,J )-diisopropyltartrate, followed by the addition of diethylzinc and substituted hydroximoyl chlorides 46, the isoxazolidines 47 are formed with impressive enantioselectivities of up to 96% ee (Scheme 6.33) [76]. 

A variety of triazole-based monophosphines (ClickPhos) 141 have been prepared via efficient 1,3-dipolar cycloaddition of readily available azides and acetylenes and their palladium complexes provided excellent yields in the amination reactions and Suzuki-Miyaura coupling reactions of unactivated aryl chlorides <06JOC3928>. A novel P,N-type ligand family (ClickPhine) is easily accessible using the Cu(I)-catalyzed azide-alkyne cycloaddition reaction and was tested in palladium-catalyzed allylic alkylation reactions <06OL3227>. Novel chiral ligands, (S)-(+)-l-substituted aryl-4-(l-phenyl) ethylformamido-5-amino-1,2,3-triazoles 142,... 

Density functional theory computational studies have been used to determine die importance of secondary orbital interactions for the stability of transition-state structures for die 4 + 2-cycloaddition of furan with cyclopropene.175 Kinetic studies of die 2 + 4-cycloaddition of 2-cyclopropylidene acetates with furan and dimethylful-vene suggest a mechanism involving diradicals or zwitterions as intermediates.176 Cyclopropene, produced by die reaction of allyl chloride with sodium bis(bimediyl-silyl)amide, reacts with 1,3-diphenylisobenzofuran to produce both endo- and exo-Diels-Alder cycloadducts isolated for the first tune.177... 

Cycloadditions. Silver perchlorate converts the l,l-dimcthyl-2-(tri-methylsiloxy)allyl chloride (1) and related allylic chlorides into an oxyallyl cation (a), which reacts with 1,3-dienes to form seven-membered ketones, often in high yield, particularly in reactions conducted in nitromethane. 

Similar conclusions are drawn by Cvetanovic et al. from their results of ozonization of alkenes in the gas phase (9) and in CC14 solution (10). The rate constants for the ozonolysis of chloroethylenes and allyl chloride, in CC14 solution, indicate (11) that the rate of ozone attack decreases rapidly as the number of chlorine atoms in the olefin molecules is increased. However, to explain the departures from simple correlations, in some cases steric effects and the dipolar character of ozone had to be invoked (10). The relevance of the dipolar character of ozone in its reactions has also been stressed by Huisgen (12), who provided evidence that the ozone—olefin reaction is usually a 1,3-dipolar cycloaddition. 

Silver(I) compounds are known to promote different kinds of cycloaddition. Reactions of 2-alkoxyallyl halides with 1,3-dienes in the presence of silver(I) compounds provide a beneficial route to cycloheptanones [2,3]. When a mixture of 2-(trimethyl-siloxy)allyl chloride 1 and cyclopentadiene (2) is treated with 2 equiv. AgC104 in THF-ether (1 2) at 0 °C, bicyclo[3.2.1]oct-6-en-3-one 3 is produced in 91 % yield [3] (Sch. 1). The 2-(trimethylsiloxy)allyl cation 4 is believed to be involved as a reactive species in the reaction. 

Stereoselective Diels-Alder reactions have been reported in several cases. Enantioselective Diels-Alder reactions of l-phenoxycarbonyl-l,2-dihydropyridine with 1-alkylated acryloyl-pyrazolidin-3-ones using a chiral cationic palla-dium-phophinooxazolidine catalyst afforded chiral isoquinuclidines with excellent enantioselectivity <2005TL5677>. Bismuth(lll) chloride-mediated diasteroselective intramolecular [4-f2] cycloaddition reactions of A-allyl derivatives of pyrazole aldehydes led to fused sulfur-containing pyrazole heterocycles <2003SC3063>. A highly diastereoselective intramolecular hetero-Diels-Alder approach toward tetracyclic pyrazoles from 5-(3-methyl-2-butenylthio)-3-methyl-l-phenyl-4-pyrazolecarboxaldehyde has been reported <1997SL1155>. 

Substituted 5-vinyl-2,3-dihydro-1,4-dioxins (150), prepared by dehydration of allylic alcohols (142) with mesyl chloride-triethylamine or thionyl chloride-pyridine, undergo [4 -I- 2] cycloaddition reactions with various dienophiles to give the adducts (151). Exposure of (151), obtained by Diels-Alder reaction with dimethyl alkynedicarboxylate, to l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) followed by acidic hydrolysis affords the highly functionalized diesters (152) <88JOC5672>. 

PolyDADMAC polymers are used for potable water clarification, waste water treatment, and textile processing. They are commercially available as solutions with solids as high as 70% and molecnlar weights ranging from 10,000 to 500,000 Da. These polymers are synthesized by the free radical solntion polymerization of DADMAC monomer, obtained from the reaction of allyl chloride, dimethylamine, and sodium hydroxide in an aqueous solution. The structure of polyDADMAC consists of abont 98% five-member pyrrodinium rings from an internal radical cycloaddition reaction and 2% pendant double bonds from the radical addition across one of the allylic double bonds (Fig. 19.3) [6]. 

Similar to the cycloaddition of allyl cations30, allenyl cations have been found to undergo cycloadditions with alkenes to afford bicyclic compounds31. The allenyl cations were generated from propargyl chlorides by treatment with Lewis acids. This reaction sequence proceeds via the cyclization 34 -------> 3532, in spite of the fact that... 

The reaction of 1,3-cyclohexadiene with la at a temperature of — 50°C gives a 97 3 mixture of 1,4-allylsilylated product, trara-3-allyl-6-(trimethylsilyl)cyclohexene and 1,2-allylsilylated product, tra 5-3-allyl-4-(trimethylsilyl)cyclohexene, in quantitative yield. At the same temperature, the [3 -I- 2] cycloaddition product is detected only in trace amounts after 1 h. As the reaction mixture is warmed to — 10°C, the allylsilylated compounds are converted to the [3-1-2] cycloaddition product (72%). When purified tra 5-3-allyl-6-(trimethylsilyl)cyclohexene and tra i-3-allyl-4-(tri-methylsilyl)cyclohexene are treated separately under the same reaction conditions, the former compound is converted to the [3 -I- 2] cycloaddition product (major) and 3-(trimethylsilyl)propylbenzene [Eq. (11)], while the latter compound is converted to polymeric materials without giving any [3-1-2] cycloaddition product. The reaction rates of allylsilylation and [3-1-2] annulation are also accelerated by the addition of trimethylchlorosilane to aluminum chloride, as observed in other allylsilylation reactions. 

Allylic nitro compounds containing a suitable dipolarophile undergo Diels-Alder cycloaddition to alkenes in the presence of tin(lV) chloride affording cyclic nitronic esters (Scheme 16).26 Nitronic ester (59) could not be isolated but spontaneously cyclized to the 5,5-fiised cyclic product (60), isolated in 68% yield. The nitronic esters (61a) and (61b) were isolated from the Diels-Alder reaction and could be separated. Heating (61a) in refluxing benzene afforded the 5,6-fused dipolar cydization product (62a) in 93% (68% overall) yield (61b) likewise afforded (62b) in 62% (11% overall) yield. Either (62a) or (62b) could be converted to the tricyclic lactam (63) by catalytic hydrogenolysis followed by lactamiza-... 

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