1226993-31-2Relevant academic research and scientific papers
Development and applications of remote stereocontrol using allylic organobismuth reagents
Basar, Norazah,Donnelly, Sam,Sirat, Hasnah M.,Thomas, Eric J.
, p. 8476 - 8505 (2013/12/04)
Reactions of 5-benzyloxy-4-methylpent-2-enyl(tributyl)stannane with aldehydes promoted by bismuth(iii) iodide were usefully stereoselective in favour of the (E)-1,5-anti-6-benzyloxy-5-methylalk-3-en-1-ols. Similar stereoselectivity was observed for reactions of analogous 5-benzyloxy-4- methylpent-2-enyl bromides with aldehydes when promoted by a low valency bismuth species prepared by reduction of bismuth(iii) triiodide with powdered zinc so providing a "tin-free" procedure. The analogous reactions of 4-benzyloxypent-2-enyl(tributyl)stannane with aldehydes promoted by bismuth(iii) iodide were also stereoselective but gave lower yields. Attempted 1,6-stereocontrol using these reactions resulted in only modest stereoselectivities. Aspects of the chemistry of the products were studied in particular their stereoselective conversion into aliphatic compounds with methyl bearing stereogenic centres at 1,5,9,13- and 1,3,5-positions along the aliphatic chain. Mechanistically, allylic organobismuth species may be involved in both sets of reactions but this was not confirmed although the similar stereoselectivities observed for both the bismuth(iii) iodide mediated reactions of the pent-2-enylstannanes and the low-valency bismuth promoted reactions of the pent-2-enyl bromides are consistent with participation of similar intermediates.
1,5-stereocontrol in bismuth-mediated reactions between aldehydes and allyl bromides: Stereoselective synthesis of open-chain all-syn- and anti, anti-1,3,5-disposed trimethylalkanes
Bazar, Norazah,Donnelly, Sam,Liu, Hao,Thomas, Eric J.
scheme or table, p. 575 - 578 (2010/09/18)
The reaction of 5-benzyloxy-2,4-dimethylpent-2-enyl bromide with the bismuth species generated by reduction of bismuth(III) iodide by zinc powder gives an intermediate which reacts with aldehydes with useful levels of stereocontrol in favour of 1,5-anti-(3E)-5-methylalk-3-enols. Manipulation of protecting groups, stereoselective hydrogenation, and tosylate displacement using a higher-order cyanomethylcuprate leads to either all-syn or anti, anti-1,3,5-disposed trimethylalkanes. Georg Thieme Verlag Stuttgart.
