Schopf’s base

Reduction of berberinephenolbetaine (121) with zinc in acetic acid afforded tetrahydroberberine (26) and its isomer. The structure of the latter was shown to be the isoindolobenzazepine 458, commonly referred to as Schopf s base VI, and its formation mechanism was also postulated (Scheme 93) (224). Recently 458 was isolated and named as chilenamine. 

Hofmann degradation of the quarternary base of the methylammonium salt of Schopf s base IV (66) has been shown to lead to the olefin 67 and the macrocyclic amine 68 (73HCA553). 

N-Demethylation and acylation of the azepines 70 with acetic anhydride gave y-lactames 71 in high yield they were transformed into Schopf s bases IV (72) by treatment with B2H6 (72CJC2022). 

Photochemical formation of a biphenyl linkage in 119 to give the tetracyclic compound 120 could be achieved in 4.4% yield (72TL5031). A photocyclization of the phthalimidine 121 to 122, which subsequently transformed into Schopf s base IV (71) (R = H), proceeded in 21.5% yield (71TL4867). Similarly, 123 reacted to give the Cephalotaxus alkaloid synthon (124) (76CC505). 

The red substance possesses the structure of SchifF s base XXII 393, 457, 539) which on hydrogenation affords the compound XXIII. Oxidation of this compound with mercury(II) acetate yields an unsaturated lactam, XXIV, which exhibits a characteristic UV spectrum. A similar lactam is afforded by Schopf s base VI (XXV) (440). 

Teitel et al. prepared tetracyclic benzazepineisoindole, i.e., Schopf s base VI (104a), from /3-hydrastine (100, 675). This base is a convenient intermediate for further chemical transformation into the protopine skeleton Hofmann degradation of the base VI yields the compounds 105 (isoindoline structure) and 106. The 10-membered trans- (108b) and cis-dibenzazecine (106) were converted via 107 into a -allocryptopine (101b) in poor yield (Scheme 38). 

The Earth began forming about 4.6 billion years (Ga) ago. The first 600 to 800 million years (Ma) of Earth s existence have been erased by the constant early bombardment of asteroids and comets (Arrhenius and Lepland 2000 Delsemme 2001 Ehrenfreund and Men ten 2002 Wharton 2002). The earliest geologic evidence for life on Earth dates to 3.5 to 3.8 Ga (Schopf and Packer 1987 Mojzsis et al. 1996 Ehrenfreund and Menten 2002 Stetter 2002 Wharton 2002). Based on this evidence, it has been argued that life on Earth developed rapidly within about 200 to 300 Ma. During this interval, the Earth evolved from a hot dry rock to a cool wet world. Evidence suggests that the... 

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