Electron transfer from trialkyltin radicals to nitrosugars: the synthesis of C-glycosides with tertiary anomeric carbon atoms

Ring-Closing Olefin Metathesis of 3,3′-(D-Glycopyranosylidene)bis(1-propene) Compounds as a Route to Anomeric Spiro Sugars

“…Indeed, such compounds had been isolated in trace amounts in the course of our previous investigation 1. Considering that there are only a few scattered synthetically useful routes, based either on free radical2 or on ionic3,4 approaches to C , C ‐disubstituted glycopyranosyl compounds, while access to C , C ‐spirocyclic glycosides5,6 often involves carbene intermediates,7−10 we anticipated that radical‐based allylation of these glycosyl dihalides would be a useful and straightforward method applicable to the synthesis of acetylated 3,3′‐( D ‐glycopyranosylidene)bis(1‐propenes). Such compounds appeared ideally suited for ring‐closing olefin metathesis (RCM)11−13 to afford new unsaturated spiro sugar derivatives.…”

Behaviour of the Primary Nitro Group Under Denitration Conditions

“…16 The reason for inactivity of primary nitro compounds in the denitration reaction is not yet clear, but a possible reason is that their carbon-nitrogen bond is harder to break than that of tertiary and activated secondary' nitro compounds (a-nitroketones, a-nitroesters or a-nitroalkenes). 2a The fact that inactivated secondary nitro groups are denitrated under more drastic conditions using a large excess of TBTH, also confirms the previous hypothesis.…”

[2+3] CycloadditionsBetween Nitroalkenes and Camphor-Derived OxazolineN-Oxidesand Radical Denitration of the Adducts

“…9 The radical denitration may be associated with inter-or intramolecular addition to a radical acceptor. 10 Cycloadducts 4a and 4b, when treated with excess tributyl tin hydride and AIBN, underwent the radical denitration under slightly milder conditions than described (refluxing benzene) to give the unfunctionalized adducts 5a and 5b in good yields and stereoselectivity. Compound 5a (R 2 = Ph) was obtained as a single stereoisomer, whereas compound 5b (R 2 = n-Bu) was obtained as a 9:1 mixture of stereoisomers.…”