Phosphine-catalyzed enantioselective and diastereodivergent [3+2] cyclization for the construction of oxetane dispirooxindole skeletons.

We have developed a phosphine catalyzed asymmetric [3+2] cyclization of 3-oxetanone derived MBH carbonates with activated methyleneoxindole, to construct oxetane dispirooxindole skeletons. Diastereodivergent synthesis was realized via the control of the phosphine catalyst. The (-)-DIOP provides the syn diastereoisomers, while the spiro phosphine (R)-SITCP achieves the anti -epimers.