Cyclopropanation epoxidation

The reaction accommodates halides, esters, ethers, nitriles, cyclopropanes, epoxides, alcohols and nitio groups. Even carbohydrates can be used.492-494 However, vinylic halides afford aldehydes and ketones... 

An account on telluronium and sulfonium ylides has briefly described the development of ylide olefination, cyclopropanation, epoxidation, and aziridination.56 Optically active m-2-substituted vinylaziridines (22) have been synthesized by the reaction of jV-r-butylsulfinylimines with telluronium ylides with excellent diastereoselectivity (g) (de > 98%) in good to excellent yields (56-98%) (Scheme ll).57... 

Like cyclopropane, epoxides have a large amount of ring strain and are much more reactive than normal ethers. Because of this ring strain, one carbon-oxygen bond of an... 

Depending on the mode of generation, a carbene may be initially formed in either the singlet or triplet state, irrespective of its stability. Common methods used for the generation of carbenes include photolytic, thermal, or metal catalyzed decomposition of diazocompounds, elimination of halogenfrom gem-dihalides, elimination of Hx from CHX3, decomposition of ketenes, thermolysis of a-halo-mercury compounds and cycloelimination of shelf stable substrates such as cyclopropanes, epoxides, aziridines and diazirines. 

The cleavage of a single bond (allylic or benzylic C-0 and C-N, C-X, C-S, N-N, N-O, 0-0 bonds, opening of cyclopropane, epoxides and aziridine by catalytic hydrogenation) is known as hydrogenolysis. Dehalogenation is favoured by basic conditions in the presence of a metal catalyst, Pd. The ease of dehalogenation decreases in the order I > Br > Cl > R... 

Stereochemistry Alkene Cyclopropane Epoxide coupling constants because (1) the C-C bond is longer (2) there... 

Reactions of ethyl diazoacetates. D can insert into O-H, S-H, and N-H bom I alkenes, carbonyl compounds, and im cyclopropanes, epoxides, and aziridines. i N< presence of MTO and PhjP). 

Enantioselective organocatalytic a-heterofimctionalization of active methines to give versatile intermediates for the synthesis of natural products and pharmaceuticals (2002 to mid-2011) 12RCA385. Enantioselective synthesis of natural epoxyquinoids 13COS2. Enzymatic chemistry of cyclopropane, epoxide, and aziridine biosynthesis 12CRV1681. 

Potassium acetate is used as the source of acetate anion in a range of addition and substitution reactions of activated cyclopropanes, epoxides, alkyl, aUyl, and benzyl electrophiles. 

Palladium-catalysed arylation of diethyl a-diazomethylphosphonate (529) with aryl iodides (530) has been described as an efficient pathway for generation of arylated diazophosphonates (531). The synthetic utility of the newly obtained diazo compound (531) (R = N02) has been futher demonstrated in cyclopropanation, epoxidation, N-H and O-H insertion reactions leading to products (532)-(535) (Scheme 156). ... 

Having established the capacity of chiral amines to catalyze asymmetric [4-1-2] and [3-1-2] reactions of unsaturated aldehydes, researchers sought to extend this olefin-activation platform to [2-t-l] reactions to produce three-membered rings. Amazing organocatalytic [2-t-l] reactions, including cyclopropanation, epoxidation, and aziridination, were developed. 

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