5-formamido-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide from 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide (10-formyl THF route): step 1/1. {ECO:0000256|HAMAP-Rule:MF_00139, ECO:0000256|SAAS:SAAS00342392}.