Allyl ethyl sulfone

Among the non-tin-based reagents for radical allylation, Zard et al. provided some notable examples (e.g., allyl ethyl sulfone, Scheme 25.47), as well as developing synthetic procedures for radical vinylation. ... 

The kinetics of decomposition of dimethylsulfone (DMS) benzyl methyl sulfone (BMS) and allyl methyl sulfone (AMS) were sudied by the toluene carrier flow technique over the temperature ranges 510-640 °C, 390-480 °C and 360-460 °C, respectively . The products of all three reactions contained CH4, SO2, ethyl-... 

Others (ethyl, fert-butyl, neopentyl, allyl amines, sulfones, ether, amides) ZnEt2/H20 78... 

Fig. 1 Reaction scheme for the synthesis of the 2 -0-allyluridine building block Reagents i, l,3-dichlorO l,l,3,3-tetraisopropyldisiloxane in pyridine ii, chlorotri-methylsilane, and triethylamine in 1,2-dichloroethane, iii, 2-mesitylenesulfonyl chloride, triethylamine, and 4-dimethyIaminopyndine in dichloromethane iv, 2,6-dichlorophenol, l,4-diazabicyclo[2 2.2]octane and triethylamine v, p-toluene sulfonic acid monohydrate in THF/dichloromethane, vi, allyl ethyl carbonate, l,4-bis(diphenylphosphino)butane and tris(dibenzylideneacetone)dipalladium(0) in tetrahydrofuran, vii, tetrabutylammonium fluoride in tetrahydrofuran viii, 2-nitro-benzaldoxime and 1,1,3,3-tetramethylguanidine in acetonitrile, ix, 4,4 -dimethoxytrityl chloride and triethylamine in pyridine x, 2-cyanoethoxy M -diisopropyl-aminochlorophosphine and //,iV-diisopropylethyiamine in 1,2-dichloroethane.

The aziridine aldehyde 56 undergoes a facile Baylis-Hillman reaction with methyl or ethyl acrylate, acrylonitrile, methyl vinyl ketone, and vinyl sulfone [60]. The adducts 57 were obtained as mixtures of syn- and anfz-diastereomers. The synthetic utility of the Baylis-Hillman adducts was also investigated. With acetic anhydride in pyridine an SN2 -type substitution of the initially formed allylic acetate by an acetoxy group takes place to give product 58. Nucleophilic reactions of this product with, e. g., morpholine, thiol/Et3N, or sodium azide in DMSO resulted in an apparent displacement of the acetoxy group. Tentatively, this result may be explained by invoking the initial formation of an ionic intermediate 59, which is then followed by the reaction with the nucleophile as shown in Scheme 43. 

Vinyl ethers can also be generated by thermal elimination reactions. For example, base-catalyzed conjugate addition of allyl alcohols to phenyl vinyl sulfone generates 2-(phenylsulfinyl)ethyl ethers that can undergo elimination at 200° C.223 The sigmatropic... 

For the addition of ethylene, EtOAc as solvent was particularly advantageous and gave 418 in 60% yield (Scheme 6.86). The monosubstituted ethylenes 1-hexene, vinylcyclohexane, allyltrimethylsilane, allyl alcohol, ethyl vinyl ether, vinyl acetate and N-vinyl-2-pyrrolidone furnished [2 + 2]-cycloadducts of the type 419 in yields of 54—100%. Mixtures of [2 + 2]-cycloadducts of the types 419 and 420 were formed with vinylcyclopropane, styrene and derivatives substituted at the phenyl group, acrylonitrile, methyl acrylate and phenyl vinyl thioether (yields of 56-76%), in which the diastereomers 419 predominated up to a ratio of 2.5 1 except in the case of the styrenes, where this ratio was 1 1. The Hammett p value for the addition of the styrenes to 417 turned out to be -0.54, suggesting that there is little charge separation in the transition state [155]. In the case of 6, the p value was determined as +0.79 (see Section 6.3.1) and indicates a slight polarization in the opposite direction. This astounding variety of substrates for 417 is contrasted by only a few monosubstituted ethylenes whose addition products with 417 could not be observed or were formed in only small amounts phenyl vinyl ether, vinyl bromide, (perfluorobutyl)-ethylene, phenyl vinyl sulfoxide and sulfone, methyl vinyl ketone and the vinylpyri-dines. 

The sulfone moiety was reductively removed and the TBS ether was cleaved chemoselectively in the presence of a TPS ether to afford a primary alcohol (Scheme 13). The alcohol was transformed into the corresponding bromide that served as alkylating agent for the deprotonated ethyl 2-(di-ethylphosphono)propionate. Bromination and phosphonate alkylation were performed in a one-pot procedure [33]. The TPS protecting group was removed and the alcohol was then oxidized to afford the aldehyde 68 [42]. An intramolecular HWE reaction under Masamune-Roush conditions provided a macrocycle as a mixture of double bond isomers [43]. The ElZ isomers were separated after the reduction of the a, -unsaturated ester to the allylic alcohol 84. Deprotection of the tertiary alcohol and protection of the prima-... 

Table 3 Bi(OTf)3-catalyzed allylation of ethyl carbamate-derived sulfones 3 with allyltri-methylsilane...

The literature reports direct grafting by gamma-rays exposure of Nylon fibers or films to the following monomers carbon monoxide (/65), ethylene (157), propylene (157), acetylene (166), butadiene (157.162,163), styrene (158, 161,163,167,168), vinyl chloride (157,163), vinyl fluoride (169-172), vinyl acetate (161,163,173), vinyl propionate (161), vinyl butyrate (161), vinyl crotonate (161), vinyl 2-ethyl hexanoate (161), acrylic add (173,174), methyl acrylate (162, 163), ethyl acrylate (162,163), allyl acrylate (163), methyl methacrylate (28,161, 163,164), butyl methacrylate (161), acrylamide (158), methylol acrylamide (163), acrylonitrile (157,160-163, 167, 175-179), divinyl sulfone (161), vinyl pyridine (167,173), vinyl pyrrolidone (28) and triallyl cyanurate (158). 

Treatment of the 2-pyrrolyl allyl thioether (498) with acetic anhydride and quinoline at 170 °C (or in A jV-dimethylaniline at ca. 100 °C) results in a thio-Claisen rearrangement to give the 5-(3-allyl-2-pyrrolyl) thioacetate (499), whilst peracid oxidation of (498) produces the non-rearranged sulfone in low yield and Raney nickel reduction of (498) yields 3-propylpyrrole (78CJC221). The polyphosphoric acid-catalyzed cyclization of (2-pyrrolylthio) acetic acid (501 R = R = H) somewhat unexpectedly yields (502) via the Spiro intermediate, instead of forming the expected oxothiolane (500), which can be obtained by a Dieckmann cyclization of ethyl (3-ethoxycarbonyl-2-pyrrolylthio) acetate (501 R = Et, R = C02Et) (B-77MI30506). 

This zinc-promoted reaction has been used with a variety of carbonyl compounds. Thus, the Luche conditions were applied in a synthesis of (-1-)-muscarine using an aldehyde derived from ethyl lactate [109]. Allyl halide condensation onto a-ketoamides of proline benzyl ester gave good diastereoselec-tivity when performed in the presence of zinc dust and pyridinium p-toluene-sulfonate in a water/THF mixture. In this way, a-hydroxy ketones were obtained with good enantioselectivity after removal of the chiral auxiliary [110]. Reactions of allyl bromide under the Luche conditions with y-aldo esters afforded y-hydroxy esters, which were converted in a one-pot reaction to y-allyl-y-butyro-lactones (Scheme 22) [111]. 

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