Reductive cyclization enones by a titanium catalyst

The reductive cyclization of an alkene or an alkyne with a heteroatom containing functional group is now possible with the help of an early transition metal catalysts like titanium. Early transformtion metal catalysts are often incompatible with polar functional groups, but in this type of transformation, enones containing allylic ethers or esters are tolerated. Efforts towards the development of more synthetically useful methods including those that afford more functionalized and/or enantiomerically enriched products are in progress.