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Alkynyl aziridines

The synthetically important subclass of alkynyl aziridines was included in a recent review <02COC539>, specifically from the standpoint of preparation and ring opening reactions with carbon nucleophiles. Such substrates (e.g. 178) tend to suffer Sn2 attack from Grignard reagents to give aminoallenes (e.g. 179). [Pg.96]

Wannaporn, D. and Ishikawa, T. (2005) Chirality transfer from guanidinium ylides to 3-alkenyl (or 3-alkynyl) aziridine-2-carboxylates and application to the syntheses of (2/J,35)-3-hydro-xyleucinate and D-erythro-sphingosine. The Journal of Organic Chemistry, 70, 9399-9406. [Pg.143]

Nucleophilic attack by a heteroatom, such as nitrogen and oxygen, in the reaction of alkynyl amines and alkynyl ethers (Section 27.2.1), alkynyl oxiranes and alkynyl aziridines (Section 27.2.2), propargylic esters (Section 27.2.3), alkynyl oximes (Section 27.2.4), and allenyl and methylenecyclopropyl ketones (Section 27.2.5), forming a carbon-heteroatom bond. [Pg.744]

Skeletal rearrangement of alkynyl oxiranes and alkynyl aziridines is an attractive method to synthesize highly substituted furans and pyrroles under mild reaction conditions. Decades ago, mercury(II)/acid-catalyzed reactions of alkynyl oxiranes... [Pg.754]

Skeletal rearrangement of alkynyl aziridines efficiently affords multisubstituted pyrroles [34]. In particular, Davies and Martin reported that the counterion of the gold catalyst determined the reaction pathway the reaction of 62 using PPhsAuOTs... [Pg.755]

Chemla and Ferreira effected lithiozincation of TMS propargyl chloride to prepare chloroal-lenylzinc bromide reagents (Table 21)33. Subsequent reaction of these reagents with N-t-butyl-substituted sulfoximines yielded the related traws-sulfoxinyl aziridines, arising from internal displacement of the chloride substituent of the anti sulfinamide adduct. A transition state in which the f-BuSO group is eclipsed with the alkynyl (vs R) substituent accounts for the preferred formation of the major A-sulfinyl diastereomer (equation 41). [Pg.451]

Recent progress on the use of hypervalent iodine reagents for the construction of carbon-het-eroatom (N, O, P, S, Se, Te, X) bonds is reviewed. Reactions of aryl-A3-iodanes with organic substrates are considered first and are loosely organized by functional group, separate sections being devoted to carbon-azide and carbon-fluorine bond formation. Arylations and alkenyla-tions of nucleophilic species with diaryliodonium and alkenyl(aryl)iodonium salts, and a variety of transformations of alkynyl(aryl)iodonium salts with heteroatom nucleophiles are then detailed. Finally, the use of sulfonyliminoiodanes as aziridination and amidation reagents, and reactions of iodonium enolates formally derived from monoketones are summarized. [Pg.137]

Conversion of dihydrofuran and dihydropyrrole A-triisopropylbenzenesul fonyl aziridines into alkynyl amino alcohols occurs with s-butyllithium-PMDETA (Scheme 64). A mechanism has been proposed.100... [Pg.463]

The intramolecular nitrone-alkene cycloaddition reaction of monocyclic 2-azetidinone-tethered alkenyl(alkynyl) aldehydes 211, 214, and 216 with Ar-aIkylhydroxylamincs has been developed as an efficient route to prepare carbacepham derivatives 212, 215, and 217, respectively (Scheme 40). Bridged cycloadducts 212 were further transformed into l-amino-3-hydroxy carbacephams 213 by treatment with Zn in aqueous acetic acid at 75 °C. The aziridine carbaldehyde 217 may arise from thermal sigmatropic rearrangement. However, formation of compound 215 should be explained as the result of a formal reverse-Cope elimination reaction of the intermediate ct-hydroxy-hydroxylamine C1999TL5391, 2000TL1647, 2005EJ01680>. [Pg.155]

Alkynylation of aziridines can be effected through the copper-catalyzed ring opening with acetylides. For example, lithium phenylacetylide engages in smooth nucleophilic attack of A-tosyl-7-azabicyclo[4.1.0]heptane 160 in the presence of copper(i) triflate to provide the cyclohexyl alkyne 161 in excellent yield (Scheme 42) <2004SL1691>. [Pg.18]

This catalytic system was successfully applied to the alkynylation of tosyl aziridine with adjacent ether functionality this should provide a promising method for the synthesis of amino alcohols. Treatment of tosyl aziridine 81 with PhC CLi in the presence of catalytic Mc3Al in toluene at 0 °C for 5 h gave rise to the corresponding alkynylation product 82 in 66 % yield (Sch. 53), whereas reaction in the absence of Me3Al proceeded sluggishly under similar reaction conditions (7 % yield). The control experiment with simple aziridine 83, in which addition of catalytic McaAl had almost no influence on the reaction rate, supports the proposed catalytic cycle its efficacy is based on the formation of the pentacoordinate organoaluminum complex. [Pg.222]

This chapter focuses the attention on the reactions of nonstabilized carbanionic compounds such as alkyl, vinyl, aryl, alkynyl metals, etc., and the chemistry of the stabilized system, i.e. allylic, propargylic or oxaallylic carbanions is presented in Volume 2 of this series. Electrophiles with C=X bonite which are discussed include aldehydes, ketones, epoxides, aziridines, acetals, orthoesters and imines, all of which turn into highly reactive electrophiles in the presence of Lewis acids. [Pg.326]

The most salient commonality among the 210 carcinogens that are positive in Salmonella is the electrophilicity that is intrinsic to the molecule or introduced by enzymatic modification. The former can be thought of as ultimate mutagens and include known or presumable alkylating and acylating agents diazo compounds, nitrosamides, nitrosoureas, dimethylcarbamyl chloride, diaryl alkynyl carbamates, aziridines, oxiranes, thiirane,... [Pg.421]


See other pages where Alkynyl aziridines is mentioned: [Pg.68]    [Pg.35]    [Pg.74]    [Pg.78]    [Pg.754]    [Pg.68]    [Pg.35]    [Pg.74]    [Pg.78]    [Pg.754]    [Pg.19]    [Pg.3]    [Pg.479]    [Pg.40]    [Pg.110]    [Pg.36]    [Pg.1466]    [Pg.74]    [Pg.2250]    [Pg.532]    [Pg.19]    [Pg.209]    [Pg.17]    [Pg.18]    [Pg.672]    [Pg.672]    [Pg.22]    [Pg.101]    [Pg.705]    [Pg.110]    [Pg.781]    [Pg.56]    [Pg.63]   
See also in sourсe #XX -- [ Pg.78 ]




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