Geminal systems. Communication 29. Reactions of N-chloro-N-methoxy-N′,N′-dimethylurea with N-nucleophiles

Conclusions In the reaction of N-chloro-N-methoxy-N,N-dimethylurea with amines, a nucleophilic substitution of the chlorine atom at the N atom takes place to form N-alkoxyhydrazines, which are stable in the reaction with Me₃N, pyridine, toluenesulfonamides, and give products of further transformations with Me₂NH and MeONHMe.For Communication 28 see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 606–610, March, 1986.     

Geminal systems. 15. Chemical properties of N-chloro-N-alkoxy-N-tert-alkylamines

Conclusions N-chloro-N-alkoxy-N-tert-alkylamines react exclusively with CN^– and SCN^– and partially with Et^– and AcO^– to give nucleophilic substitution products at the nitrogen atom. These compounds react with AcO^– and water to give nitroso compounds, with EtS^– and Ph₃ P to give azoxy compounds, and with AgF and AgNO₃ to give products of more complex transformations.For communication 14, see ref. [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2320–2326, October, 1981.     

Trimethylsilylated N-alkyl-substituted carbamates: II. Alcoholysis of trimethylsilyl N,N-dimethylcarbamate

The reaction of trimethylsilyl N,N-dimethylcarbamate with the sterically hindered alcohol 2-methylbutan-2-ol has been studied kinetically. The reaction shows autocatalytic character, and an equation has been derived which satisfactorily describes the kinetic behaviour. A mechanism is suggested for the reaction.     

Geminal systems. 16. Reactions of N-chloro-N-alkoxy-N-alkylamines with amines

Conclusions The reactions of N-chloro-N-alkoxy-N-tert-alkylamines with amines are characterized by nucleophilic substitution at the nitrogen atom with formation of the corresponding N-alkoxyhydrazines which are stable in the case of ethyleneimine and pyridine; give diazenes as in the case of MeNH₂, EtNH₂, and Me₂ or yield products of further transformations as in the case of NH₃, Me₂NH, and MeO(Me)NH. Nucleophilic substitution is repressed in the reaction with Et₂NH and Et₃ N by one-electron reduction with the formation of azoxy compounds.For Communication 15, see previous article [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2327–2334, October, 1981.     

Geminal systems. 50. Synthesis and alcoholysis of N-acyloxy-N-alkoxy derivatives of ureas,carbamates, and benzamides

Procedures were developed for the synthesis of N-acyloxy-N-alkoxy derivatives of ureas, carbamates, and benzamides by the reactions of the corresponding N-alkoxy-N-chloro derivatives with sodium carboxylates in MeCN. N-Chloro-N-ethoxy-p-toluenesulfonamide was inert in this reaction. Alcoholysis of N-acyloxy-N-alkoxy derivatives of ureas, carbamates, and tert-alkylamines afforded the corresponding N,N-dialkoxy derivatives, whereas alcoholysis of N-acetoxy-N-ethoxybenzamide gave rise to alkyl benzoates.     

Geminal dicarboxylates as carbonyl surrogates for asymmetric synthesis. Part II. Scope and applications.

An enantioselective synthesis of allylic esters has been achieved by a novel asymmetric alkylation of allylic gem-dicarboxylates. The catalyst derived from palladium(0) and R,R-1,2-di(2'-diphenylphosphinobenzamido)cyclohexene efficiently induced the alkylation process with a variety of nucleophiles to provide allylic esters as products in good yield. High regio- and enantioselectivities were observed in the alkylation with most nucleophiles derived from malonate, whereas a modest level of ee's was obtained in the reactions with less reactive nucleophiles such as bis(phenylsulfonyl)ethane. In the latter case, a slow addition procedure proved effective, leading to significantly improved ee's. The utility of the alkylation products was demonstrated by several synthetically useful transformations including allylic isomerizations, allylic alkylations, and Claisen rearrangements. Using these reactions, the chirality of the initial allylic carbon-oxygen bond could be transferred to new carbon-oxygen, carbon-carbon, or carbon-nitrogen bonds in a predictable fashion with high stereochemical fidelity. The conversion of gem-diesters to chiral esters by the substitution reaction is the equivalent of an asymmetric carbonyl addition by stabilized nucleophiles. In conjunction with the subsequent reactions that occur with high stereospecificity, allylic gem-dicarboxylates serve as synthons for a double allylic transformation.     

Diethyl N,N-dimethylaminomethylenemalonate in the synthesis of fused heterocyclic systems

The reactions of diethyl N,N-dimethylaminomethylenemalonate ( 3 ) with N- and C- nucleophiles were studied. In the reaction of 3 with heterocyclic amines 4 , with the amino group attached at α-position in respect to the ring nitrogen atom, substitution of the dimethylamino group in 3 with the heterocyclic amino took place to give diethyl heteroarylaminomethylenemalonates 5 , which can cyclize into fused azino- 6 or azolopyrimidinones 7 . In the reaction of 3 with the compound with an active methylene group attached at α-position in regard to the ring nitrogen atom, such as pyridinylacetonitrile ( 8 ), ethyl pyridinyl- ( 9 ), and quinolinylacetate ( 10 ), fused quinolizines 11 and 12 , and benzo[c]quinolizine 13 were formed, respectively. Heterocyclic systems with an active or potentially active methylene group incorporated in the ring system, such as pyrazole 14 , pyrimidine 15 , and pyridine derivative 18 , gave with 3 fused pyranones 16, 17 , and 19 , and dihydroxynaphthalenes 22 and 23 naphtho[2,1-b]pyranones 24 and 25 .     

Asymmetric nitrogen. 73. Geminal systems. 47. Configuration stability and mechanism for inversion of N-chloroxaziridines

We have studied the kinetics of racemization and thermolysis of (+)-2-chloro-3,3-pentamethyleneoxaziridine (I). The activation energy determined for inversion of the nitrogen atom in (I) in n-heptane is 28.9 kcal/mole lower than the value calculated (ab initio, 3–21G) for 2-chloroxaziridine (II). Based on this and also on the increase in the inversion rate of (I) with an increase in the polarity of the solvent and the entropy of activation (–43.5 cal/mole·K, n-heptane), we conclude that the mechanism for inversion of N-chloroxaziridines is nonclassical, by means of reversible ionization of the N-Cl bond through a solvate-unseparated ion pair.For the previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1816–1819, August, 1989.     

S(N)2 Mechanism for Alcoholysis, Aminolysis, and Hydrolysis of Acetyl Chloride

First-order solvolysis rate constants are reported for solvolyses of acetyl chloride in methanol and MeOD, and in binary aqueous mixtures with acetone, acetonitrile, ethanol, methanol, and trifluoroethanol at 0 degrees C. Product selectivities (S = [MeCOOR]/[MeCOOH] x [water]/[alcohol]) are reported for solvolyses in ethanol/ and methanol/water at 0 degrees C. Solvolyses of acetyl chloride show a high sensitivity to changes in solvent ionizing power, consistent with C-Cl bond cleavage. As the solvent is varied from pure ethanol (or methanol) to water, S values and rate-rate profiles show no evidence for the change in reaction channel observed for solvolyses of benzoyl and trimethylacetyl chlorides. However, using rate ratios in 40% ethanol/water and 97% trifluoroethanol/water (solvents of similar ionizing power but different nucleophilicities) to compare sensitivities to nucleophilic attack, solvolyses of acetyl chloride are over 20-fold more sensitive to nucleophilic attack than benzoyl chloride. The solvent isotope effect of 1.29 (MeOH/MeOD) for acetyl chloride is similar to that for p-methoxybenzoyl chloride (1.22) and is lower than for benzoyl chloride (1.55). Second-order rate constants for aminolyses of acetyl chloride with m-nitroaniline in methanol at 0 degrees C show that acetyl chloride behaves similarly to p-methoxybenzoyl chloride, whereas benzoyl chloride is 40-fold more sensitive to the added amine. The results indicate mechanistic differences between solvolyses of acetyl and benzoyl chlorides, and an S(N)2 mechanism is proposed for solvolyses and aminolyses by m-nitroaniline of acetyl chloride (i.e. these reactions are probably not carbonyl additions, but a strong sensitivity to nucleophilic attack accounts for their high rates).