Cryptopleurine

The trans-phenanthroquinolizidine alkaloid cryptopleurine has been shown to have the (R) configuration (28) by comparison of o.r.d. and c.d. data with those of the trans-phenanthroindolizidine alkaloids of established stereochemistry.  

Yamada, E. Fujita, and H. Murata, Chem. Pharm. Bull., 1978, 26, 2513. 

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A similar strategy served to carry out the last step of an asymmetric synthesis of the alkaloid (—)-cryptopleurine 12. Compound 331, prepared from the known chiral starting material (l )-( )-4-(tributylstannyl)but-3-en-2-ol, underwent cross-metathesis to 332 in the presence of Grubbs second-generation catalyst. Catalytic hydrogenation of the double bond in 332 with simultaneous N-deprotection, followed by acetate saponification and cyclization under Mitsunobu conditions, gave the piperidine derivative 333, which was transformed into (—)-cryptopleurine by reaction with formaldehyde in the presence of acid (Scheme 73) <2004JOC3144>. 

The quaternization of 2-pyridinecarbaldehyde with 2,3,6-trimethoxy-9-phenanthryl-methyl bromide (183) yielded a salt (184) which, when cyclized, afforded a dibenz[/i,/]acridizinium derivative (185). Reduction of the quinolizinium ring of (185) afforded ( )-cryptopleurine (57JA3287). 

The anti-tumour properties of cryptopleurine (33) continue to stimulate synthetic work in this area, and two new syntheses have been reported this year. Snieckus and co-workers25 have described a short, efficient synthesis of the alkaloid, utilizing a benzamide-directed metallation reaction (Scheme 6). In the other synthesis,26 the piperidine derivative (35), prepared by a nitrone cycloaddition reaction, is cyclized... 

Silicon (iv) chloride is an effective Lewis acid in the cyclization and subsequent dehydration steps of Herbert s synthesis of julandine and of cryptopleurine (cf. Vol. 10, p. 72).27 An early cryptopleurine synthesis has been improved.28... 

Cryptopleurine Cryptocarpa pleurosperma SOS PS - 40S subunit site (blocks... 

S PS — 40S subunit site (cf. Cryptopleurine, Tubulosine Tylocrebrine) rabbit reticulocyte PS (at 1-100) [antiamoebic, anticancer, antiviral, cytotoxic, emetic, expectorant]... 

Miscellaneous alkaloids Abikoviromycin Ageliferin Crinamine Cryptopleurine Sceptrin Didemnin Haemanthamine Hippeas trine... 

The phenanthroquinolizidine alkaloid cryptopleurine (149), which is a homologue of tyrophorine (119), was synthesized by the Weinreb group via the methylol acetate derivative (146) of an inseparable mixture of ( )- and (Z)-... 

TTie lithiation of a l,6-methano[10]annulenamide occurs selectively at the peri position, but the lithiation of fused ring aromatics t es place preferentially at the ortho (rather than peri) position,as shown by the examples in Scheme 12. Subsequent transformations of the phthalides obtained in the naphthalene example also illustrate the usefulness of this method for the annelation of aromatic rings. The preference for ortho over peri lithiation holds true for phenanthrenes as well. The selective metd-ation of trimethoxyphenanthrenamide (15) followed by phthalide synthesis as above constitute the key steps in the synthesis of the phenanthroquinolizidine alkaloid cryptopleurine and the phenanthroindoli-zidine alkaloid antofme (Scheme 13). ... 

Tylophorinine, C23H25O4N (XVb), is a tertiary base with three methoxyl groups but no A"-methyl group. Its UV-spectrum with maxima at 258, 287, and 340 mp (loge 4.61, 4.34, 2.91) is very similar to that of cryptopleurine, a 2,3,6-trimethoxyphenanthrene derivative (7). 

The asymmetric total synthesis of the phenanthroquinolizidine alkaloid (-)-cryptopleurine was reported by S. Kim et al. One of the key steps in the sequence was the thermai Overman rearrangement which took place in refluxing toluene in nearly quantitative yield and without any loss of the optical purity of the allyl trichloroimidate substrate. 

Returning to phenol ether-phenol ether coupling, synthetic septicine (59) gave ( )-tylophorine (60) on treatment with thallium trifluoroacetate, and the same reagent converted synthetic julandine (61) to ( )-cryptopleurine (62 69%). In another synthesis of tylophorine the lactam (63) was transformed with va-... 

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