2- Amino-2- acetaldehyde chloroformate

Reaction of 2-amino-2-(2-aminophenyl)acetaldehyde aroylhydrazones (109) with ethyl chloroformate gave the urethane derivatives 110. The latter underwent condensative double ring-closure to the l,2,4-triazolo[l,5-c]quinazolin-5-ones 86. Carrying out a similar reaction between 109 and guanidine furnished the 5-amino congener 111 (93JHC11) (Scheme 40). 

Amino-5-chloromethyl-3-cyanopyrazine 1-oxide with triphenylphosphine in dimethylformamide at 80-90° gave 2-amino-3-cyano-5-(triphenylphosphonio)-methylpyrazine 1-oxide chloride (97) (520) and the 5-bromomethyl analogue reacted similarly with triphenylphosphine in propan-2-ol (542). Compound (97) on hydrolysis with 30% aqueous ethanol containing a small amount of triethylamine gave 2-amino-3-cyano-5-methylpyrazine 1-oxide and thus enabled removal of the chloro substituent from the chloromethylpyrazine (529) compound (97) with triethylamine and acetaldehyde (and other aldehydes) in chloroform at room temperature gave 2-amino-3-cyano-5-(prop-l -enyl)pyrazine 1-oxide (and other alkenyl analogues) (529). 

Acetaldehyde, acrolein, 2-aminobutane, 2-amino-2-methylpropane, 2-bromo-2-chloro-l,l,l-tri luoroethane, bromomethane, 1,3-butadiene, l-chloro-l,l-difluoro-ethane, chlorofluoromethane, 2-chloro-l,3-butadiene, chloroform, 3-chloro-l-pro-... 

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