RESUMO
The idea of constitutional dynamic chemistry (CDC) and dynamic combinatorial chemistry (DCC) is widespread in the literature using the chemistry of disulfides. The synthesis of unsymmetrical diaryl disulfides is challenging due to the presence of a weak S-S bond. We report herein the synthesis of unsymmetrical diaryl disulfides from two symmetrical disulfides via a cross-metathesis reaction which was controlled by a weak sulfurâ¯iodine (Sâ¯I) interaction. The unsymmetrical disulfides were stable in acetonitrile solution in the presence of N-iodosuccinimide (NIS), and found to be reversibly photoswitchable to the symmetrical disulfides under visible light irradiation.
RESUMO
An umpolung approach for the synthesis of unsymmetrical disulfides via sulfenium ion is reported. In situ generated electrophilic sulfenium ion from electron-rich thiols reacted with second thiols to yield unsymmetrical disulfides. Using an iodine catalyst and 4-dimethylaminopyridine (DMAP)/water as promoter, the target syntheses were achieved in one pot under aerobic condition.
RESUMO
An FeCl3-catalyzed efficient strategy for the allylation reactions of 3-hydroxy-2-oxindoles with allyltrimethylsilane has been developed. The reaction affords a variety of 2-oxindoles having quaternary center at the pseudobenzylic position in an operationally simple and inexpensive procedure. Control experiments using enantioenriched 3-hydroxy-2-oxindole show that the reaction proceeds through in situ generated 2H-indol-2-one (8). The methodology presents an efficient and concise access to the pyrroloindoline alkaloids (±)-deoxyeseroline (1a), (±)-esermethole (1b), (±)-physostigmine (1c), (±)-phenserine (1d), and (±)-physovenine (1e). Eventually, we extrapolated the scope of this methodology to the formal total syntheses of dimeric cyclotyrptamine alkaloids (±)-chimonanthine (3a), (±)-folicanthine (3c), and (±)-calycanthine (4).
