GB1326360A - Nitrofuryl-pyrazolopyrimidinones - Google Patents

Abstract

1326360 Nitrofuryl-pyrazolopyrimidones CIBA-GEIGY AG 27 Oct 1970 [28 Oct 1969 9 Sept 1970 (3)] 43055/70 43056/70 52663/69 and 43054/70 Heading C2C [Also in Division A5] Novel compounds of Formula I (in which R 1 is C 1-5 alkyl or C 1-5 alkoxy-carbonyl, and R 2 is H, C 1-5 alkyl optionally substituted by one or more Cl or Br atoms, C 5-7 cycloalkyl, aralkyl of up to 12C atoms, or C 2-4 alkenyl) are prepared by (a) treating a compound of Formula II with a compound of formula R 2 .C(OR 4 ) 3 , R 2 COX or (R 2 CO) 2 O (where R 4 is C 1-3 alkyl and X is OH, halogen, C 1-3 alkoxy or C 2-3 alkenyloxy) and cyclizing the resulting intermediate without isolation, or (b) reacting a compound of Formula III with formic acid or a carboxylic acid derivative R 2 COX or (R 2 CO) 2 O (where X is as defined above except that it may not be OH) in the presence of an acidic or basic catalyst to form a nitrofurylpyrazole intermediate of Formula IV and the intermediate then cyclized with or without preliminary isolation, or (c) reacting a compound of Formula III with an excess of an acid anhydride (R 2 CO) 2 O, in the absence of a catalyst, to form a nitrofuryl-pyrazole intermediate of Formula V and subsequently protonating and hydrolysing this intermediate with or without preliminary isolation, or (d) cyclizing a compound of Formula V1 or (e) treating a compound of Formula III with an acid anhydride (R 2 CO) 2 O in the presence of an arylsulphonic acid catalyst to give a nitrofuryl-pyrazolo [3, 4-d] oxazine intermediate of Formula VII and then reacting this intermediate, with or without preliminary isolation, with ammonia or with a compound which will provide ammonia in situ under the reaction conditions. Compounds of Formula VI are prepared by acylation of the corresponding amines. Compounds I have antimicrobial activity.