Carbonyl transposition studies

Monomeric pNBS: Bis(p-nitrobenzenesulfonate) of 2,4-Hexadiyne

“…By considering substituents with increasing volume (Kitaigorodsky, 1973), one can begin with the unsubstituted BSHD diacetylene; here R is -CH2-O-SO2-C6H5 and the molecule polymerizes (Ando et al, , 1985. The fluoro-substituted compound, pFBS, where R is CH2-O-SO2-C6H4-F ( Aim6 et al, 1988;Yee, 1979), is also reactive. The chloro-substituted compound, pCBS, has both a reactive and an unreactive form Mayerle & Clarke, 1978).…”

Probes for Narcotic Receptor-Mediated Phenomena. 33.1 Construction of a Strained trans-5,6-Ring System by Displacement of a Nitro-Activated Aromatic Fluorine. Synthesis of the Penultimate Oxide-Bridged Phenylmorphans

“…), although these conditions normally furnished a mixture of products. However, exclusive formation of trans -dihydrofurans was observed with certain fused-ring aryloxyenones. , Further, irradiation of the same type of substrates in protic solvents produced exclusively the less strained cis isomer in excellent yields. ,, This heteroatom-directed photoarylation protocol was unsuccessfully attempted for the synthesis of the cis tetracyclic b-isomer of the oxide-bridged 5-phenylmorphan in our laboratory. , In addition to the photochemical approach, the only other reported synthetic pathway 12 to the simple trans tricyclic hexahydrodibenzofurans involved constructing the furan ring prior to six-membered ring formation so as to establish the desired trans geometry at the 5,6-ring junction. However, extension of this route to the synthesis of our target molecules would require incorporation of suitable functionality at C 4a and C 1 to build the piperidine ring, which might prove extremely challenging in terms of both stereochemical control and compatibility of functionality.…”

“…15,16 Further, irradiation of the same type of substrates in protic solvents produced exclusively the less strained cis isomer in excellent yields. 15,17,18 This heteroatom-directed photoarylation protocol was unsuccessfully attempted for the synthesis of the cis tetracyclic b-isomer of the oxidebridged 5-phenylmorphan in our laboratory. 5,6 In addition to the photochemical approach, the only other reported synthetic pathway 12 to the simple trans tricyclic hexahydrodibenzofurans involved constructing the furan ring prior to six-membered ring formation so as to establish the desired trans geometry at the 5,6-ring junction.…”