AZIRIDINES ,N amino

AZIRIDINE, l-amino-2-phenyl [1-Azmdin-amme, ( )-2-phenyl-], 55, 55, 114 AZIRIDINES, N-amino- [1-Azindinamines], 55,114... 

Aziridine, alkyli dene- N-ethoxycarbonyl thermolysis, 7, 78 Aziridine, N-amino-... 

C in D2O. Extensive tables are found in Lehn s review <70MI50100). Calculations of inversion barriers have met with mixed success. The MNDO SCF method gives results which compare well with experimental values, including the high barriers of Af-halo- and N-amino-aziridines, and the low ones for Af-trimethysilyl- and Af-phosphino-aziridines <80JCS(P2)1512). 

In many instances, however, the intermediate triazoline can be isolated and separately converted into the aziridine, often with poor stereoselectivity. The first practical modification to the original reaction conditions generated the (presumed) nitrenes by in situ oxidation of hydrazine derivatives. Thus, Atkinson and Rees prepared a range of N-amino aziridine derivatives by treatment of N-aminophthali-mides (and other N-aminoheterocydes) with alkenes in the presence of lead tetraacetate (Scheme 4.10) [7]. 

Nucleophiles react with NH or N-acyl oxaziridines at the nitrogen. Much of this chemistry has been carried out with cyclohexanespiro-3-oxaziridine 39 an intermediate 40 proceeds to cyclohexanone, the result being amination of the nucleophile. Transfers of NH to N-, 0-, S-, and C-nucleophiles enable the syntheses of hydrazines, N-amino-peptides, hydroxyamines, sulfenamides, thiooximes, sulfonamides, aziridines, and -amino acids. 

Scheme 33 N-Amino heterocycles which yield aziridines from alkenes and Pb(OAc)4...

Azetidines. Reaction of 7-amino alcohols with triphenylphosphine dibromide and then with triethylamine first at 0° and then at 25° results in formation of triphenylphosphine oxide and N-substituted azetidines. This method had been used previously to prepare aziridines from amino alcohols (3, 322). 

H. Paulsen and D. Stoye, Hydrazine-Reactionen IV. Darstellung und Reactionen von N-Amino-aziridine Zuckern, Chem. Ber., 102 (1969) 820-833. 

Isocyanide, benzyl-, 55, 98 Isocyanide, butyl-, 55, 98 Isocyanide, cyclohexyl-, 55,98 ISOCYANIDE, 1,1-dimethylethyl- [Isocyanide, ferr-butyl-], 55,96 Isocyanide, dodecanyl-, 55,98 Isocyanide, ethyl-, 55,98 Isocyanide, methyl-, 55, 98 Isocyanide, phenyl-, 55, 98 1/f-Isoindole-l, 3(2/I)-dione, 2-amino-[Phthalimidc, N-amino-j, 55, 115 l/y-ISOINDOLE-l,3(2//)-DIONE, trans- ( )-2-(2,3-diphenyl-l-aziridinyl)-[Aziridine, frans-2,3-diphenyl-l-phthalimido-], 55, 115 ISOXAZOLE, 3-(4-chlorophenyl)-5-(4-methoxyphenyl)-, 55, 39 Isoxazole, 5-C4-chlorophenyl)-3-(4-meth-oxyphenyl)-, 55, 42... 

C,HrXN-N(C,H,)2 N-Amino phenyl-aziridine Girard reagents Tosylhydrazine HN NH Alkyl azides Picryl azide Cyanogen azide Ng, Dicyclohexyl-ammonium azide Guanidinium azides Azidinium salts HNs NH2OH... 

N- Aminoaziridines have been converted to alkenes by reaction with a variety of oxidizing agents (70JA1784). Usually, the deamination reaction is stereospecific. The oxidation of l-amino-2,3-diphenylaziridines with manganese dioxide, however, was not stereospecific. The trans compound gives entirely frans-stilbene, whereas the cfs-aziridine forms a mixture of 85% trans- and 15% c -aikene. cw-Stilbene is not isomerized to trans under the reaction conditions, and the results are explained in terms of an azamine intermediate which can isomerize through a tautomeric equilibrium. 

As described in Section 2.3.2, vinylaziridines are versatile intermediates for the stereoselective synthesis of (E)-alkene dipeptide isosteres. One of the simplest methods for the synthesis of alkene isosteres such as 242 and 243 via aziridine derivatives of type 240 and 241 (Scheme 2.59) involves the use of chiral anti- and syn-amino alcohols 238 and 239, synthesizable in turn from various chiral amino aldehydes 237. However, when a chiral N-protected amino aldehyde derived from a natural ot-amino acid is treated with an organometallic reagent such as vinylmag-nesium bromide, a mixture of anti- and syn-amino alcohols 238 and 239 is always obtained. Highly stereoselective syntheses of either anti- or syn-amino alcohols 238 or 239, and hence 2,3-trans- or 2,3-as-3-alkyl-2-vinylaziridines 240 or 241, from readily available amino aldehydes 237 had thus hitherto been difficult. Ibuka and coworkers overcame this difficulty by developing an extremely useful epimerization of vinylaziridines. Palladium(0)-catalyzed reactions of 2,3-trons-2-vinylaziri-dines 240 afforded the thermodynamically more stable 2,3-cis isomers 241 predominantly over 240 (241 240 >94 6) through 7i-allylpalladium intermediates, in accordance with ab initio calculations [29]. This epimerization allowed a highly stereoselective synthesis of (E) -alkene dipeptide isosteres 243 with the desired L,L-... 

An aza-Darzens reaction, involving the addition of chloromethylphosphonate anions to enantiopure N-sulfinimines, has also been developed by Davis and others for the asymmetric synthesis of aziridine-2-phosphonates [81-84], As an example, treatment of the lithium anion generated from dimethyl chloromethylphos-phonate (93 Scheme 3.30) with N-sulfmimine (Ss)-92 gave the a-chloro-P-amino phosphonate 94, which could be isolated in 51% yield. Cyclization of 94 with n-BuLi gave cis-N-sulfmylaziridine-2-phosphonate 95 in 82% yield [81],... 

With Sulfur Nucleophiles N-Carboxy-protected aziridine-2-carboxylates react with thiols to give P-mercapto-ot-amino acid derivatives. The reaction is usually catalyzed by BF3 and the yields range from fair to excellent [15, 16, 108-111]. With N-unprotected 3-substituted aziridine-2-carboxylates, the ring-opening with thiols usually takes place with anti stereoselectivity, especially in the case of the C-3 aliphatic substituted substrates. In cases in which C-3 is aromatic, however, the stereoselectivity has been found to be a function of the substitution pattern on the aromatic ring 3-p-methoxy ph eri yl-su bs li In led aziridines 143a (Scheme 3.51) and... 

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