Microsoft does not support the use of BitLocker on the bootable partition of a virtual hard disk. BitLocker support in a virtual machine (2036142) | VMware KB
BitLocker Frequently Asked Questions (FAQ)
"Does BitLocker support virtual hard disks (VHDs)?
BitLocker is not supported on bootable VHDs, but BitLocker is supported on data volume VHDs, such as those used by clusters, if you are running Windows 8, Windows 8.1, Windows Server 2012 or Windows Server 2012 R2."
Not sure what your requirements are, but perhaps vSphere Virtual Machine Encryption, might be worth a read; Virtual Machine Encryption .
Thanks
Simon