P-Nitrophenyl isothiocyanate

Satchell and Satchell" reported a kinetic study on the aminolysis of p-nitrophenyl isothiocyanate with primary amines and anilines in diethyl ether and isooctane as solvents. The detailed analysis reveals that the aminolysis occurs via a zwitterionic intermediate, T , which undergoes subsequent proton transfer catalyzed by a second amine molecule (equation 12). Added carboxylic acids form inactive 1 2 amine-acid complexes with strong basic amines and inhibit aminolysis, but with weak bases the acids form only a negligible amount of complex and they catalyze the aminolysis. 

A soln. of l-cyclohexyl-2-phenyl-3-p-toluoylaziridine and p-nitrophenyl isothiocyanate refluxed 17 hrs. in dry benzene -> 3-cyclohexyl-5-p-nitrophenylamino-2-phenyl-4-p-toluoyl 4-thiazoline. Y 54%. J. W. Lown,G. Dallas, and T. W. Maloney, Can. J. Chem. 47, 3557 (1969) aziridine ring expansion, review, s. F. N. Gladysheva, A. P. Sineokov, and V. S. Etlis, Russ. Chem. Rev. 39, 118 (1970) (Eng. transL) heterocyclics by aziridine ring expansion, review, s. J. W. Lown, Record Chem. Progr. 32, 51 (1971). 

In the reaction of p-nitrophenyl isothiocyanate with AT,W-tetramehtyl-W"-n-butyl-guanidine 49 an exchange reaction with formation of n-butyl isothiocyanate 50 is observed. ... 

A 1,3-dipole, generated from the aziridine 91, also undergoes a [3-1-2] cycloaddition reaction with p-nitrophenyl isothiocyanate to give a thiazolidine derivative 92 . ... 

The yields from the reactions, carried out at room temperature and a pressure of 2-4 at, increase with increasing electronegativity of the substituent X. The yield with phenyl isocyanate is 13%, with p-chlorophenyl isocyanate 55% and with p-nitrophenyl isocyanate it is 100%. Primary and secondary carba-moylphosphines cannot be isolated even when equi-molar quantities of phosphine and isocyanate are used. Their intermediate formation is probable but apparently they are more reactive towards isocyanates than phosphine itself. Similarly, phosphine does not react with free cyanic acid whereas primary and secondary phosphines react with cyanic acid, as with isocyanates, to form the corresponding carbamoylphosphines Attempts to make phosphine react with phenyl isothiocyanate did not succeed... 

Transesterification. Zwitterionic adduct of 4-pyrrolidinopyridine and an electron-deficient aryl isothiocyanate (e.g., p-nitrophenyl and 3,5-bis(trifluoromethyl)phenyl isothiocyanates) catalyzes transesterification of methyl esters, requiring only stoichiometric quantity of the alcohol. The reaction is best performed by azeotropic refluxing, with assistance of 5A-molecular sieves to absorb the liberated MeOH. 

Becker et al. specifically inactivated the biotin transport system of E. coli using biotin p-nitrophenyl ester. The lactose transport protein of E. coli was labeled by AT-bromoacetyl-/8-D-galactopyranosylamine. In the only reported attempt to isolate an affinity labeled protein, glucose 6-isothiocyanate, which is an affinity label for the glucose transport system in human erythrocytes, gave enough nonspecific labeling of other membrane proteins to render identification of the transport protein difficult. 

Only a few examples of the formation of 1,2,4-triazines by this fragment combination have been published, all cases being 1,2,4-benzotriazine syntheses. 2-Nitroaniline reacts with cyanamides to give 2-nitrophenylguanidines (601) which cyclize under basic conditions to 3-amino-l,2,4-benzotriazine 1-oxides (602) <78HC(33)189, p.699). With benzoyl isothiocyanate it affords Ar-(2-nitrophenyl)-N -benzoylthiourea (603), which cyclizes to l,2,4-benzotriazine-3-thione 1-oxide (604) (80MI21900).. 

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