Synthesis of 2,2 ',2 '',2 '''-(1,2-ethanediylidene)tetrafuran and Diels-Alder reaction with dimethyl acetylenedicarboxylate
A one step procedure has been found that converts 2,2'-methylenedifuran (1) into 2,2,',2",2'''-(1,2-ethanediylidene)tetrafuran (4: 1,1,2,2-tetrakis(furan-2-yl)ethane). This compound adopts two similar C-2V-symmetrical conformations (4A and 4A') in the crystalline state in which the C-H bond of the 1,2-ethanediylidene moieties is anti-periplanar with the C(2)-O bond of the vicinal furan-2-yl groups. Tetrafuran (4) is little reactive toward dienophiles with normal electronic demand. With dimethyl acetylenedicarboxylate a single 1:1 adduct (8) (dimethyl (1RS,2RS,2aRS,5SR,5aRS,6RS,8aRS,8bSR)-1,2-di(furan-2-yl)-1,2-dihydro-5H, 6H-2a,5:6,8a-diepoxyacenaphthylene-5a,8b-dicarboxylate) was isolated. Its structure was established by single crystal X-Ray radiocrystallography.
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Keywords: furan ; 7-oxabicyclo[2.2.1]heptene ; Diels-Alder addition ; conformational ; analysis ; crystal and molecular structure ; Asymmetric-synthesis ; double-bond ; conformational-analysis ; systems ; cycloadditions ; derivatives ; route
Swiss Fed Inst Technol, Inst Mol & Biol Chem, EPFL, BCH, CH-1015 Lausanne, Switzerland. Univ Lausanne, Inst Crystallog, CH-1015 Lausanne, Switzerland.
Record created on 2005-11-09, modified on 2016-08-08