Coproduire is a french third group verb. So, this verb is irregular and do not follow a regular conjugation pattern like first or second group verbs. Follow this link to see all the endings of the conjugation of most of the third group verbs : 
conjugation rules and endings for the second group verbs.
																																																																																																																																						
Coproduire verb is conjugated in negative form. The placement of the negative adverb follow the following rules:
									
 - the adverb 
« ne » is placed after the pronoun and before the verb.
									
 - in simple tenses, the adverbs (
« ne ...pas », 
« ne...plus », 
« ne...jamais », etc...) surround the verb 
coproduire.
									
 - in compound tenses or in passive voice, the negative adverbs surround the auxiliary.