I. I. Chervin

Asymmetrical nonbridgehead nitrogen-XXVI: Synthesis, configurational stability, and resolution of N,N-dialkoxyamines into antipodes

Abstract Alkoxyamines with tertiary N-alkyl substituents were chlorinated to N-chloro-N-alkoxyamines whose reaction with alcohols enabled synthesis of N,N-dialkoxyamines. The DNMR method was used to determine the barriers of inversion of these compounds. Alkaline hydrolysis ( 13 ) followed by subsequent reactions with R -(+)- and S -(−)-α-phenylethylamine yielded diastereomeric salts (+ 29 and − 29 ) whose crystallization and subsequent esterification resulted in optically active acyclic amines (− 13 and + 13 ) with the asymmetric center only at the N atom in the open chain.

Asymmetric nitrogen—41: Stereochemistry of bicyclic 1,2-cis-diaziridines

Abstract The twisting of 5- and 6-membered rings in bicyclic cis-diaziridines—1,5-diazabicyclo [3.1.0]hexanes 12–17 and l,6-diazabicyclo[4.1.0]heptane 18—is a rapid process in the time scale of 1H- and 13C-NMR even at -80°. According to the 1H- and 13C-NMR spectra, 1,5-diazabicyclo [3.1.0]hexanes 12,13,15a,15b and 16a,16b do, exist mostly in the boat form ; only the introduction of endo substituents into position 3 or 6 leads to the population of the chair, as is the case with 14 and 17. 2,4-Dialkyl substituted 1,5-diaza- and 1,3,5-triazabicyclo[3.1.0]hexanes are formed via a transition cyclization state similar in its geometry to the initial chair-shaped N-chlorodi(tri)azanes.

Asymmetrical nonbridgehead nitrogen—XXIV: Complete separation into antipodes and absolute configuration of chiralic N-alkoxyaziridines

Optically active derivatives of 1 - methoxyaziridine - 2,2 - dicarboxylic acid have been obtained: the diethyl ester S-(− 1a) by kinetic enrichment under the action of 1-ephedrine; the diamines R-(+2d) and S-(−2f) by crystallization from 1-methyllactate; the diamide S-(−2g) by asymmetric inversion reaction at the N atom while heating in 1-methyllacetate. The basic possibility of 1-alkoxyaziridine reactions with retention of optical activity (ammonolysis and reduction with LAH4) has been demonstrated for S-(−1a) and R-(+1). 1-Methoxy - aziridine - 2,2 - dicarboxylic acid cis-ethyl ester 4 has been completely separated into antipodes 1R, 2S-(+4) and 1S, 2R-(−4) which under the effect of diazoethane afford diethyl esters R-(+1) and S-(−1) with optical purity of 96.2 and 93.8% (determined by PMR using a chiralic shift-reagent). On the basis of X-ray analysis of monoamides of 1 - methoxyaziridine - 2,2 - dicarboxylic acid ethyl ester and of salt +7 the trans-specificity of ammonolysis and hydrolysis of 1 and the absolute configurations of all the optically active derivatives obtained were established.

Asymmetric nitrogen - 70. geminal systems - 44. trialkoxy-amines(orthonitrites). Synthesis and properties

Abstract The chlorination of acyclic N,N-dialkoxyamines under the action of tert-BuOCl results in the formation of unstable N-chloro-N,N-dialkoxyamines which in situ react with sodium methoxide to give previously unknown trialkoxyamines (orthonitrites). The properties of the N-chloro-N,N-dialkoxy-and trialkoxyamines have been demonstrated to be similar to those of their carbon analogues: dialkoxyalkylchlorides and orthoesters, respectively.

Asymmetric nitrogen-lxxi. asymmetric synthesis and lactonization of 1-β-hydroxyalkylaziridine-2-carboxylic esters into 4-oxa-1-azabicyclo[4.1.0]heptan-5-ones☆

Abstract Epimeric mixtures of 1-β-hydroxya1kyl zirid1ne-il-carboxy1ic esters were prepared by the Gabriel-Cromwell reaction, followed by their separation by liquid chromatography with subsequent lactonization of each epimer in the presence of base to give pure enantiomers and diastereomers of lactones differing as to the aziridine (C-2) carbon configuration. According to PMR spectroscopy data, twisted boat is the most preferred six-membered cycle configuration in 4-oxa-1-azabicyc1o[4.1,0]- heptane-J-ones in solution. The absolute configurations of carbon atoms in chiral lactones were determined by CD-spectroscopy. Epimers of 1-β-hydroxyalkylaziridine- 2-carboxylic esters sharing the same carbon configuration (α-substituent at nitrogen) but differing in C-2 configuration undergo lactonization at different rate. A rational explanation of this phenomenon is provided

Sterically hindered inversion of nitrogen atoms in cyclic hydrazines:N,N′-dialkyl-1,3,4-oxadiazolidines; 1,3,4-thiadiazolidine; and 4,5-benzo-1,2,3,6-tetrahydropyridazine

N,N′-Diisopropyl-substituted 1,3,4-oxadiazolidine3c, 1,3,4-thiadiazolidine6, 4,5-benzo-1,2,3,6-tetrahydropyridazine8, and new 3,4-dialkyl-1,3,4-oxadiazolidines9–14 were synthesized and studied. The configurational stability of the N atoms does not change on going from compound3c to itsS-analog6 and decreases in the case of pyridazine8. 3,4-Di-tert-alkyl-1,3,4-oxadiazolidines3d and11–14 were found to be promising objectes for optical resolution.

Geminal systems: 19 Reactions of aminomethylphosphines with electrophilic reagents

Conclusions1.In the reactions of aminomethylphosphines with the acylating reagents RCOCl, ClCN, and PhNCO the electrophilic attack is carried out at the phosphorus atom with cleavage of the C-P bond and the formation of acyl-, cyano-, and carbamoylphosphines.2.Aminomethylphosphines display dual reactivity with respect to alkylating reagents. The attack of MeI is directed at the phosphorus atom to form aminomethylphosphonium salts, where as PhCH2Br, MeOSO2F, and HCl react at the nitrogen atom, producing phosphinomethylammonium salts. The regiospecificity of the reaction depends on the basicity of the N atom, the size of the substituents on the P atom, and the type of alkylating reagent.

ASYMMETRIC NITROGEN .57. INVESTIGATION OF THE STEREOCHEMISTRY OF AZIRIDINECARBOXYLIC ACID-DERIVATIVES BY NMR

ConclusionsThe preferred trans configuration of 1,2-disubstituted aziridines and cis configuration of NH-aziridine-2-carboxylic esters were established by means of the1H and13C NMR spectra and the two-dimensional NOESY and COSY-45 spectra.

Oligomers of aziridines and N-?-aziridinoethylamides

Conclusions1.An efficient method of aziridine dimer synthesis is presented involving reaction of aziridine with esters of strong organic acids followed by alkaline hydrolysis of the resultant N-acyl derivatives.2.New N-acyl and carbamoyl derivatives of aziridine dimer and trimer were synthesized.3.Linear and branched isomers of aziridine tetramer and also diastereomers of 2-methylaziridine dimer were isolated and characterized.4.An efficient regiospecific synthesis of 2,2-dimethylaziridine dimer and trimer was developed.

Asymmetric nitrogen Communication 48. Geminal systems. communication 32 NH-dialkoxyamines: synthesis, mydroxy-and aminomethylation, nmr spectra, and configurational stability

Conclusions1.Alkaline hydrolysis of N,N-dialkoxy-N′,N′-dimethylureas gives NH-dialkoxyamines.2.N-Hydroxymethyl- and N-aminomethyl-N,N,-dialkoxyamines have been synthesized and their reactions with nucleophiles and electrophiles have been studied.3.The configurational stability of the N atom in NH-dialkoxyamines and their derivatives has been determined by NMR.