https://www.ncbi.nlm.nih.gov/pmc/tools/get-metadata/
https://www.ncbi.nlm.nih.gov/pmc/tools/developers/#use-cases
This E-Summary call retrieves article metadata for a PMCID:
https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esummary.fcgi?db=pmc&id=3539452&retmode=json
The returned data includes the PubMed ID (PMID) for this article, so you can do a further call to get PubMed metadata for the same article:
https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esummary.fcgi?db=pubmed&id=22368089&retmode=json