Synthesis of (-)-agelastatin A by [3.3] sigmatropic rearrangement of allyl cyanate

Total synthesis of (-)-agelastatin A has been achieved starting from l-arabitol. The highlights in our synthesis include the preparation of vicinal diamine moiety by [3.3] sigmatropic rearrangement of allyl cyanate and construction of central ring-C with ring-closing metathesis.     

Synthesis of an Octacyclic C60 Fragment

Fragments of buckminsterfullerene (C₆₀) include the monumental three compounds corannulene, sumanene, and truxene. These three have served as leading molecules in ongoing research for curved, fused, and π-extended polyaromatic materials. Achieving more structural variations that join the ranks of these three archetypes remains challenging. Herein we report synthesis of an octacyclic hydrocarbon that is an unexplored C₆₀-fragment, namely, a 4,11-dihydrodiindeno[7,1,2-ghi:7′,1′,2′-pqr]chrysene (C₂₈H₁₆, which we named Metelykene). The key to success was solution-compatible synthesis in which double pentagonal rings flank hexagonal ones. This solution-phase approach, coupled with the resulting non-planar π-conjugation, is so straightforward that it offers an entry to a derivative such as a cardo aromatic monomer.     

Rotaxane Synthesis by an End-Capping Strategy via Swelling Axle-Phenols

A method for rotaxane synthesis by enlargement of the size of the terminal phenol group of the axle component by aromatic bromination has been developed. This method may be regarded as an end-capping strategy involving the swelling of the phenol group at the axle terminal. The advantages of the present strategy include: ready availability of axle components with a variety of swelling precursors, wide product scope (19 examples given including a [3]rotaxane), mild conditions for the swelling process, rich potential for the derivatization of the brominated rotaxanes, and possible release of the axle component by degradative dethreading of the thermally stable brominated rotaxanes under the basic conditions.