Modified nucleosides from nitrones: a new and efficient stereoselective approach to isoxazolidinyl thymidine derivatives

Tunable Diastereoselection of Biased Rigid Systems by Lewis Acid Induced Conformational Effects: A Rationalization of the Vinylation of Cyclic Nitrones En Route to Polyhydroxylated Pyrrolidines

“…[18] The addition of nitrone 12 to the reaction mixture did not produce any product and the nitrone was recovered. [19] The same result was obtained when nitrone 12 was treated with trivinylaluminum tetrahydrofuranate. [20] In no case was transfer of vinyl or ethyl moieties to the nitrone observed, [21] thus indicating that the reaction takes place through delivery of the vinyl group from the Grignard reagent in agreement with the mechanism previously reported.…”

New developments in nucleophilic additions to nitrones

“…The addition of the sodium enolate derived from methyl acetate gives directly the cyclic adduct, no evidence of the open-chain hydroxylamine being observed (Scheme 13) [33]. This is probably due to the basic medium of the reaction which favors the intramolecular cyclization of the intermediate hydroxyamino anion.…”

The approach to the synthesis of novel amino-C-glycosides

“…The reactivity was slightly related to the property of the substituent on nitrones (5) and (8), that is, the electron-withdrawing group was beneficial to the reaction. It should be mentioned that Lewis acids, such as ZnCl 2 , ZnBr 2 , AlCl 3 , BF 3 ·OEt 2 , Yb(OTf) 3 were not effective to the reaction, even though it has been reported that some Lewis acids could efficiently promote the 1,3-dipolar cycloadditions of some nitrones and electron-rich alkenes such as enolic compounds in a stereoselective way [34][35][36][37]. On the other hand, the isomerization of exo-glucal (1a) to the corresponding glucal (11) may probably be one of the reasons that resulted in the low yields of the cycloaddition reactions due to the much low reactivity of (11) to the nitrone (8).…”