78824-64-3Relevant academic research and scientific papers
Synthetic Studies with 7-Functionalised Norbornenes, and their Synthesis by a Silicon-Controlled Carbocation Rearrangement
Fleming, Ian,Michael, Joseph P.
, p. 1549 - 1556 (2007/10/02)
As part of a projected synthesis of gelsemine (1), the synthesis of dimethyl 7-oxobicyclohept-5-ene-2-endo,3-exo-dicarboxylate (5) is described.The route involves the silicon-controlled rearrangement of 5-exo-bromo-3-exo-methoxycarbonyl-7-anti-trimethylsilylbicycloheptane-2,6-carbolactone (9), catalysed by silver ions in methanol, to give dimethyl 7-syn-hydroxybicyclohept-5-ene-2-endo,3-exo-dicarboxylate (11).Some related reactions show that a 7-trimethylsilyl group in a norbornene can be used to synthesise other 7-functionalised norbornenes.Thus the epoxide (13) of methyl 7-anty-trimethylsilylbicyclohept-5-ene-2-endo-carboxylate (12) rearranges on treatment with boron trifluoride-ether to give methyl 7-anti-hydroxybicyclohept-5-ene-2-exo-carboxylate (14), and treatment of (12) with bromine gives mainly the rearranged bromide, methyl 7-anti-bromobicyclohept-5-ene-2-exo-carboxylate (16).Some limitations in this approach to 7-functionalised norbornenes are also described.
