Small Organo-molecular Catalysis Organic Reactions In Hexamethyl-disiloxane

Polysiloxanes are hydrophobic, chemically resistant polymer. PDMS origin from SiO2 instead petroleum is available commercially and continuable. Small polysiloxannes such as 1,1,1,3,3,3-hexamethyldisiloxane (HMDS) are usually used as a block agent in organic silicone chemistry. Up to now, no reported about HMDS played a role as a solvent for organic synthesis. It is physiological intact to body and a biologically acceptable, inexpensive, eco-friendly, and its boiling point is 100.1℃that is easy to be recoverable. Based on these properties of HMDS, we envision that it may offer a"safe"and environmentally friendly alternative solvent. In this thesis, small organo-molecular catalysis organic reactions use hexamethyl-disiloxane (HMDS) sa a green medium have been studied in detail.In partⅠ,the direct aldol reactions catalyzed by L-proline in HMDS were studied. The results indicated that high chemical yield (96%), high diastereoselectivity (anti/syn=99/1) and good enantioselectivity(ee>99%) were obtained when the reactions catalyzed with 10 mol% L-proline in HMDS. The results in these catalytic systems were superiorer to those of the correspounding resctions in organic media in terms of the catalyst unload, reaction yield, and the enantioselectivity.In partⅡ, an efficient and practical method is described for the ring-opening reaction of N-tosylaziridine with various thiols catalyzed by thiourea in HMDS under mild conditions. The results indicated that thiourea is an good organocatalyst for the ring-opening reaction of N-tosylaziridine with various thiols. under optimal conditions, the ring-opening reactiions gave rise to the correspondingβ-amino sulfides in good to excellent yields.These results in these work indicated that HMDS is a efficient, environmental friendly alternative solvent for the various of organic transformations...