In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: We present a 43 - year - old man who developed a coronary aneurysm in the right coronary artery 6 months after receiving a paclitaxel - eluting stent .
### Output Text:
We present a 43 - year - old man who developed a coronary aneurysm in the right coronary artery 6 months after receiving a <span class="chemical">paclitaxel</span> - eluting stent . 