Is there an adapter to mount a XTR Di2 front derailleur on a Cannondale Cannondale Scalpel 29r? picture of stock mount
Images from BikeRadar:
Done a bit of looking about and it looks like your frame takes an E-Type direct mount. Since the new XTR Di2 front mech uses a modular mounting system you'd simply buy the E-Type mount, bolt it to the frame and attach the FD to this.
I've gone off the photo above to determine FD mount type. Looks like the E-Type to me, so the mount here should be all you need. The picture on Chain Reaction Cycles doesn't show the correct mount. It should look like the image below!