3-amino-2//-azirines

Nucleophilic additions to 3-alkoxy (86RTC456) and 3-amino-2//-azirines (91AG(E>238) are especially well studied, e.g. Scheme 19. Many of these reactions involve assistance by protonation of the nitrogen. 

Amino-2//-azirines as amino acid equivalents 86U3. 3-Amino-2//-azirines as synthons for a,a-disubstituted a-amino acids in the synthesis of heterocycles and peptides 91AG(E)238. 

The application of 3-amino-2//-azirines as amino acid equivalents and their use in the synthesis of cyclic dipeptides presumably includes ring enlargement steps [14]. The formation of 12- or 15-membered cyclodepsipeptides from open chain precursors possibly includes ring enlargement steps [3] [15]. 

It can be prepared by treatment of 3-amino-2//-azirines (e.g. 3-(dimethyl-amino)-2,2-dimethyl-2//-azirine) with an amino acid or peptide and, finally, with a (u-hydroxyacid. The formation of the oxazolone, VI/121, is observed when VI/120 is treated with acid. The ring enlargement step, the conversion of VI/121 to VI/122, is observed under the same conditions. The transformation of (-)-(R,R)2- 2-[2-(2-hydroxy-2-phenylacetamido)-2-methylpropionato]-2-phenylacetamido -N,N,2-trimethylpropionamide (VI/123) to (-)-(R,R)-3,3,9,9-tetramethyl-6,12-diphenyl-l,7-dioxa-4,10-diazacyclododecane-2,5,8,ll-tetrone (VI/126) in dry toluene/hydrochloric acid at 100° was observed in a 88 % yield. Compounds VI/124 and VI/125 are discussed to be intermediates. In an analogous reaction sequence cyclopeptides can be synthesized [93]. 

The introduction of a,a-disubstituted amino acids into peptides is sometimes troublesome. A recent, easy access to enantiomerically pure 3-amino-2//-azirines offers an elegant way for... 

Aziridines in the synthesis of azomethine ylides 89AHC(45)231. Aziridines in the synthesis of natural products 86AHC(39)I81. Azirines as intermediates in pyrrole formation 87KGS1299. 3-Amino-2-//-azirines, synthesis and properties 90KGS867. Ethynylaziridines 87MI6. 

The enamine-azide 1,3-dipolar cycloaddition has been found to be thermally reversible, e.g. (282) (283) (tsjhcsos). 4//-Triazoles (284), formed from sodium azide and a-chloroenamines bearing methoxycarbonyl and alkyl groups at the /3-position, give on thermolysis aromatic triazoles (285) and/or 3-amino-2//-azirines (286). On photolysis only azirines (286) are obtained (8occ94o). 

The synthesis of optically active 3-amino-2/-/-azirines was carried out using a modified Neber rearrangement in the laboratory of I.P. Piskunova. The optically active amidoximes were acylated using mesyl chloride to give 0-mesyl derivatives that upon treatment with sodium methoxide afforded the desired product with high diastereoselectivity. 

CC1583>. The reaction of 3-amino-2//-azirine with isothiazolin-3-ones leads to 4//-l,2,5-thiadiazocin-6(5//) one 1,1-dioxides (Equation (1)) <91HCA1002>. 

In Chart 4 are listed some of the most popular and useful acceptor-donor reactophores that have been used in combinatorial and parallel synthesis such as epoxides, episulfides, imines, p-diketones. 2,2-Disubstituted 3-amino-2//-azirines constitute a highly reactive class of acceptor-donor reactophores that have been shown to be useful for the generation of a range of diverse heterocycles under mild reaction conditions. Furthermore, isocyanates, isothiocyanates and carbodiimides belong to the class of prototypical acceptor-donor reactophores as they exhibit high reactivity and are readily available. 

A nice example of a high-yielding two component reaction incorporating all atoms in the products constitutes the ring-expansion reaction of 3-amino-2//-azirines 7 with NH-acidic heterocycles as shown in the following examples (Scheme 3.2.2). 

Finally, Rens and Ghosez reported in 1970 on treatment of a-chloroenamines 87 with sodium azide, that led to 3-amino-2//-azirines 89 in excellent yields (Scheme 5.14, see also Chapter 6, Section 6.2 (Gilchrist Alves)). These products were explained by the... 

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