Preparation of substituted ethenes

Details Preparation of substituted ethenes Preparation of substituted ethenes

1991-07-18

1994-12-06

Ivy, C. Warren

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

564485, 564340, 546246, C07D31744, C07C20900

Patent

active

053712471

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to certain substituted ethenes, specifically certain N-substituted alkyl or arylalkyl thionitroethenamines, derivatives thereof, intermediates in the production thereof and processes for the manufacture of all the aforesaid.
2. Brief Description of the Related Art
In general terms the said family of nitroethenes is known, although certain particular nitroethenes disclosed herein are believed to be novel, and have known uses as intermediates in the manufacture of pharmaceutical compounds such as the histamine H.sub.2 antagonists containing the pharmaceutically active end group --NHC(.dbd.CHNO.sub.2)NHX wherein X is an organic radical, for example niperotidine which has the formula ##STR1##
Spanish Patent Specification No. 523448 describes the preparation of N-methyl-1-methylthio-2-nitroethenamine from the dipotassium salt of 2-nitrodithioacetic acid (1-nitro-2,2-bismercapto-ethylene) by a three stage process involving firstly the methylation of one only of the KS-groups by reaction with dimethyl sulphate, secondly the conversion of the resulting CH.sub.3 S-group into a CH.sub.3 NH-- group by reaction with methylamine and thirdly, the methylation of the second KS-group by reaction with a further quantity of dimethyl sulphate. This patent is silent as to any possibility for producing other N-substituted thionitroethenamines.
The process described in the Spanish Patent requires careful control at all stages to avoid the production of unwanted reaction products such as the bis(methylthio) derivative and is disadvantageous in requiring a repetition of the dimethyl sulphate reaction due to the toxic nature of that compound.
It is known in the chemical art that, in general, amines do not react with dianions since the lone pair electrons on the amine inhibit reaction with a molecule which is already doubly negatively charged. This inhibition does not apply to dimethyl sulphate. The processing sequence of the Spanish Patent No. 523448 is therefore in accord with current belief in the art.
The present applicant has found, however, that certain amines can be made to react directly with the 2-nitrodithioacetate dianion. This has enabled a highly selective two stage process for the production of aminosubstituted thiosubstituted nitroethenes to be developed.


SUMMARY OF THE INVENTION

The present invention provides a method for the production of a monopotassium salt useful in the production of N-substituted alkyl or arylalkyl thionitroethenamines characterised by reacting an amine selected from branched chain primary alkylamines, secondary alkylamines, arylalkylamines and heterocyclic alkylamines, wherein the alkyl moieties of said arylalkylamines and heterocyclic alkylamines are not straight chain primary amines containing a heteroatom in the chain, with the dipotassium salt of a 2-nitrodithioaliphatic acid.
This process is robust in that it does not require close control at each process step, does not oversubstitute at all during the amination to give the bisaminated derivative and can give an excellent yield.
The monopotassium salt so obtained may be alkylated or arylalkylated to give the required alkyl or arylalkyl thionitroethenamine.


DETAILED DESCRIPTION OF THE INVENTION

In the case of the simplest dipotassium salt, namely dipotassium 2-nitrodithioacetate (also known as dipotassium nitrothiolothionoacetate), and an amine, such as dimethylamine, the sequence of reactions outlined above is as follows: ##STR2## This intermediate may then be converted to N,N-dimethyl-1-methylthio-2-nitroethenamine by reaction with a methylating agent,such as dimethyl sulphate, as follows: ##STR3## These reactions proceed analogously when using other alkyl, arylalkyl or heterocyclic alkyl amines in Reaction I or other alkylating or arylalkylating agents in Reaction II.
Other amines the use of which is within the scope of the present invention may be selected from other secondary aliphatic amines, substituted or branched chain aliphatic amines, for e

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