No, you cannot directly "convert" a US tourist visa to a work visa. Instead, you must apply for a status change or a new visa. This requires a US employer to sponsor you for a suitable work visa, like an H-1B visa. Then you must file Form I-539 with the US Citizenship and Immigration Services (USCIS) before your tourist visa or authorized stay expires. You must also avoid violating your tourist visa by not working and ensuring you were legally entered and have followed the rules.