634600-90-1Relevant academic research and scientific papers
Synthesis of Non-symmetrical Dispiro-1,2,4,5-Tetraoxanes and Dispiro-1,2,4-Trioxanes Catalyzed by Silica Sulfuric Acid
Amado, Patrícia S. M.,Coelho, Jaime A. S.,Cristiano, Maria L. S.,Frija, Luís M. T.,O'neill, Paul M.
, p. 10608 - 10620 (2021)
A novel protocol for the preparation of non-symmetrical 1,2,4,5-tetraoxanes and 1,2,4-trioxanes, promoted by the heterogeneous silica sulfuric acid (SSA) catalyst, is reported. Different ketones react under mild conditions with gem-dihydroperoxides or peroxysilyl alcohols/β-hydroperoxy alcohols to generate the corresponding endoperoxides in good yields. Our mechanistic proposal, assisted by molecular orbital calculations, at the ωB97XD/def2-TZVPP/PCM(DCM)//B3LYP/6-31G(d) level of theory, enhances the role of SSA in the cyclocondensation step. This novel procedure differs from previously reported methods by using readily available and inexpensive reagents, with recyclable properties, thereby establishing a valid alternative approach for the synthesis of new biologically active endoperoxides.
Co(thd)2: A superior catalyst for aerobic epoxidation and hydroperoxysilylation of unactivated alkenes: Application to the synthesis of spiro-1,2,4-trioxanes
O'Neill, Paul M.,Hindley, Stephen,Pugh, Matthew D.,Davies, Jill,Bray, Patrick G.,Park, B. Kevin,Kapu, Dauda S.,Ward, Stephen A.,Stocks, Paul A.
, p. 8135 - 8138 (2007/10/03)
Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)cobalt(II) (Co(thd) 2), a β-diketonate prepared in a simple one-step procedure, is an excellent catalyst for aerobic epoxidation and Mukaiyama-Isayama hydroperoxysilylation of unactivated alkenes. For hydroperoxysilylation, Co(thd)2 is superior to Co(acac)2 and can catalyse oxidation of cyclic alkenes in excellent yield. Chiral β-diketonate or keto iminato catalysts failed to catalyse this reaction in an enantioselective manner and a free radical mechanism consistent with this observation is proposed. Hydroperoxysilylation of cyclohex-1-enylmethanol by Co(thd) 2 followed by addition of a ketone/TsOH provides a simple one-pot procedure for the synthesis of spiro-1,2,4-trioxane antimalarials.
