Acid Catalyzed Isomerization of Large Ring Bicyclic Alkenes: a Reevaluation of Some Betweenanene Synthetic Strategy
نویسندگان
چکیده
We recently described a remarkable acid-catalyzed isomerization of bicyclic alkenes Ia and Ib to the betweenanenes IIa and IIb. ’ This finding suggested that certain larger ring betweenanenes might possess unusual stability relative to double bond isomers and might thus be derivable from readily available bicyclic compounds via equilibrating processes. In this report we describe several attempts at implementation of this strategy which led us to question the validity of the reported isomerization.
منابع مشابه
The stereoselective formation of bicyclic enamines with bridgehead unsaturation via tandem C-H bond activation/alkenylation/electrocyclization.
Bridgehead bicyclic unsaturated enamines were prepared by a tandem rhodium-catalyzed C-H bondactivation/alkenylation/electrocyclization of alkyne-tethered unsaturated imines. These strained bicyclic enamines exhibitunique reactivity: for example, they give N-Alkylated products upon treatment with alkylating reagents and undergo doublebond isomerization to alleviate ring strain upon ...
متن کاملStereoselective hydroacylation of bicyclic alkenes with 2-hydroxybenzaldehydes catalyzed by hydroxoiridium/diene complexes.
A hydroxoiridium complex coordinated with 1,5-cyclooctadiene efficiently catalyzed the hydroacylation of bicyclic alkenes with 2-hydroxybenzaldehyde and its derivatives in high yields with high stereoselectivity.
متن کاملPhotoreactions of bicyclic aziridines with alkenes and alkynes: a novel synthetic methodology for 8-azabicyclo[3.2.1]octane derivatives.
The photochemical C-C bond cleavage of bicyclic aziridines 7 and subsequent [3 + 2] cycloaddition with electron-deficient alkenes and alkynes afforded the novel head-to-head adducts selectively and efficiently. The adducts contain the naturally occurring 8-azabicyclo[3.2.1]octane skeleton (e.g. tropane alkaloids). The aziridine 8 fused with a 6-membered ring also afforded the cycloadducts but i...
متن کاملPalladium-catalyzed [2 + 2 + 2] cocyclotrimerization of benzynes with bicyclic alkenes: an efficient route to anellated 9,10-dihydrophenanthrene derivatives and polyaromatic compounds.
An efficient method for the cocyclotrimerization of bicyclic alkenes and benzynes catalyzed by palladium phosphine complexes to give the corresponding norbornane anellated 9,10-dihydrophenanthrene derivatives is described. Bicyclic alkenes 1a-i undergo [2 + 2 + 2] cocyclotrimerization with benzynes generated from precursors 2a-d [2-(trimethylsilyl)phenyl triflate (2a), 4,5-dimethyl-2-(trimethyl...
متن کاملRing Cleavage of Some Bicylic Compounds Derived from 1,2,4-Triazine
Ring cleavage occurred when 1,2,4-triazino-1,2,4-triazines (3), (4) and (5) were treated with concentrated hydrochloric acid to yield N-substituted triazines (7) and (8). These confirm the given configuration assigned to the isomeric triazinotriazines. 6-Methyl-2-phenyl-7H-oxazolo [3,2-b][1,2,4]-triazin-7-one (9) underwent ring cleavage on treatment with sodium alkoxide to afford 3-alkoxy-1...
متن کامل