Olefinic cyclizations. IX. Further observations on the butenylcyclohexenol system

Amino-Claisen rearrangements of N-vinylisoquinuclidines in novel approaches to the synthesis of hydroisoquinolines and hydrophenanthridines

“…Interconversion of endoand exo-7-Acetylisoquinuclidenes 4. A solution containing 150 mg (0.67 mmol) of the 7-acetylisoquinuclidene carbamates 4 in an exo-endo ratio of 3:4 and ethanolic sodium methoxide (from 900 mg, 0.04 g-atom of sodium and 70 mL of ethanol) was stirred under Ar at 25 °C for 15 h. The mixture was poured into ice water and neutralized with concentrated HC1 and chloroform was extracted. The extracts were dried and concentrated in vacuo, giving 120 mg of an oil characterized by !H NMR to contain a mixture of exo-and endo-acetylisoquinuclidenes in a ratio of 3:2.…”

“…¡28.8 id) nuclidene 22 can be produced at 25 °C by stirring 20 in an acidic aqueous THF solution. Rearrangement of this new N-vinylisoquinuclidene 22 to produce 23 (79%) requires refluxing benzene temperatures and p-TsOH as catalyst.…”

“…Interestingly, the final step of this mode closely mimics analogous processes in polyolefin cationic cyclizations24 and thus should display similar stereochemical preferences for production of the cis ring fusion via axial addition to the allyl cation through a transition state having the enamino ketone side chain equatorially disposed. 25 The acid-catalyzed transformation of N-ketovinylated isoquinuclidenes to hydrophenanthridines can also be rationalized by several possible mechanisms all starting with the O-protonated salts. Thus, although kinetic protonation of several enamines has been shown to be selective for nitrogen,26 acid-base theory and experimental observations16 suggest that the carbonyl oxygen of enamino ketones is the site protonated.…”

Nonenzymic biogenetic-like olefinic cyclizations. Cyclization of 4-(trans-3,7-octadienyl)-3-methyl-2-cyclohexen-1-ol and 4-(trans, trans-7-methyl-3,7,11-dodecatrienyl)-3-methyl-2-cyclohexen-1-ol

“…The hydrocarbon fraction obtained from cyclization of tetraenol 4 showed two major peaks on gas chromatography. The component with the lower retention time (hydrocarbon A) was isolated by preparative gas chromatography in 97 % purity.…”

“…Anhydrous magnesium sulfate was added and the mixture was stirred for 2 hr. The salts were removed by filtration ; the filtrate and washings were combined and concentrated to give 350 mg (97% yield) of colorless oil: "1" 3.0 (OH) and 6.04, 6.11, 10.1, 10.3, and 11 µ (C=C); nmr 1.67 (broad s, 3 H, C=CCH3), 2.27 (s, 1 H, OH), 4.02 (broad m, 1 H, >CHO-), and 4.75-6.1 ppm (m, 5 H, vinylic). /ra«s-6-Methyl-12-(4-methoxy-2-methyIphenyl)-l,5-dodecadien-9yne (12).…”