Oxirans with nitrogen nucleophiles

In the presence of a palladium catalyst, allyl epoxides (113) react with nitrogen nucleophiles at the al-kenic carbon atom remote from the oxirane ring to give 1,4-adducts (114)." In the absence of a palladium catalyst, azide ion attacks the oxirane ring affording 1,2-adducts (115 Scheme 52 and Table 2)." Vinyl epoxide (116) gave 1,2- and 1,4-azido alcohol in a ratio of 1 1.5 irrespective of the reaction system. " Intramolecular cyclization of vinyl epoxide (117) in the presence of a palladium catalyst afforded isoquinuclidine (118 Scheme 52). ... 

Reaction of epoxides with nitrogen nucleophiles affords a variety of P-hydroxyamines and their equivalents. Comprehensive review articles have been published. In conjunction with the development of diastereoselective and enantioselective syntheses of epoxy alcohols, selective oxirane ring cleavage of 2,3-epoxy alcohols and carboxylates by nitrogen nucleophiles has become a versatile route to various amines and their equivalents. For details, the reader is referred to refs. lOSc and 103d. 

Substitution of an additional nitrogen atom onto the three-carbon side chain also serves to suppress tranquilizing activity at the expense of antispasmodic activity. Reaction of phenothia zine with epichlorohydrin by means of sodium hydride gives the epoxide 121. It should be noted that, even if initial attack in this reaction is on the epoxide, the alkoxide ion that would result from this nucleophilic addition can readily displace the adjacent chlorine to give the observed product. Opening of the oxirane with dimethylamine proceeds at the terminal position to afford the amino alcohol, 122. The amino alcohol is then converted to the halide (123). A displacement reaction with dimethylamine gives aminopromazine (124). ... 

A chiral, nonracemic oxirane, (3 )-2-[(R)-fluoro(phenyl)methyl]oxirane, can react with (chiral) amines under the influence of lithium perchlorate using either heat or microwave irradiation. This reaction sequence provides a material from which the ee of chiral a-branched amines can be determined <2005OL3829>. Guanidines serve as a useful nitrogen nucleophile for the direct conversion of epoxides to aziridines <2004JOC8504>. 

Nucleophilic Ring-opening Reactions of Oxirans.—Reactions with Oxygen and Nitrogen Nucleophiles. A series of papers have appeared that deal with the reactions of lower aliphatic alcohols (R OH) with (120 = Me) to yield (121 ... 

Polyfluoroalkyl- andperfluoroalkyl-substituted CO and CN multiple bonds as dipolarophiles. Dmzo alkanes are well known to react with carbonyl compounds, usually under very mild conditions, to give oxiranes and ketones The reaction has been interpreted as a nucleophilic attack of the diazo alkane on the carbonyl group to yield diazonium betaines or 1,2,3 oxadiazol 2 ines as reaction intermediates, which generally are too unstable to be isolated Aromatic diazo compounds react readily with partially fluorinated and perfluorinated ketones to give l,3,4-oxadiazol-3-ines m high yield At 25 °C and above, the aryloxa-diazolines lose nitrogen to give epoxides [111]... 

In contrast to HFPO, 2,2-bis(trifluoromethyl)oxirane (2) ring opens with oxygen, nitrogen, sulfur, and carbon nucleophiles at the less hindered carbon, yielding tertiary alcoholsWith diethylamine, for example, 2 affords an aminoalcohol in 83% yield. Oxirane 2 played an important role in the development of monomers from which to build highly transparent, yet readily alkali-soluble photoresist copolymers... 

Wu and coworkers developed a Cu(I)-catalyzed three-component reaction of 2-(2-ethynylphenyl)oxiranes 111, sulfonyl azides 112, and ethyl a-isocyanoacetate (113) to afford 3 5 -dihydro-l//-spiro[benzo[d]oxepme-2,4 -imidazoles] 114 as a single diastereomer (Scheme 4.24) [44]. The reaction was initiated by a Cu(I)-catalyzed [3+2] cycloaddition between azide and alkyne to generate the intermediate 115. Subsequent release of nitrogen would provide the reactive ketenimine species 116. An intramolecular nucleophilic attack of epoxide to the ketenimine afforded the intermediate 117, which underwent fragmentation to provide 118. Finally, a [3+2] cycloaddition of 118 with a-isocyanoacetate 113 afforded the observed product 114. 

Three groups of workers have studied the reactivity of thiourea towards a -unsaturated ketonesThe notable lability in the reaction course was demonstrated by the simultaneous or alternative formation of different open-chain as well as cyclic products, thus clearly indicating the occurrence of nucleophilic attacks of both the sulphur and the nitrogen atoms of thiourea on both the carbonyl carbon and the 3-carbon atom of the a 3-unsaturated ketone. Other papers reporting on the nucleophilic activity of thioureas deal with reactions of the latter with oxirans, oxaziridines," acryloyl chloride," o 3-unsaturated acids," acetylenedicarboxylic acid esters, " ethyl thiocyanoacetate," and isocyanates. ... 

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