VirtualBox can export appliance VMs to OVF format. And you can import the ovf format to VMware ESXi, however there are some trouble.
Unsupported hardware family 'virtualbox-2.2'. OVF hardware element 'ResourceType' with instance ID '5': No support for the virtual hardware device type '20' OVF hardware element 'ResourceType' with instance ID '8': No support for the virtual hardware device type '35'.
yeah, there are some tips:
First, you need export appliance using OVF extension(default is ova) in VirtualBox.
And run a python script (https://gist.github.com/eshizhan/6650285):