Two ways:
1) Click on the list you have imported. Select all leads and click Lead Actions > Salesforce > Sync Lead to SFDC
2) Create a batch campaign with the following
Smart List - Member of List, List = List 001
Flow - Sync to SFDC - Use Auto Assign Rules
More info about sync to SFDC flow step: https://community.marketo.com/MarketoArticle?id=kA050000000LAAhCAO