The total synthesis of (+-)-dasycarpidone and (+-)-epidasycarpidone

Dolby, Lloyd J.; Biere, H.

doi:10.1021/ja01012a047

Cited by 21 publications

(4 citation statements)

References 4 publications

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“…l-Benzylmethylamino-3-hexanone (6). Benzylmethylamine (500 g, 4.12 mol) was gradually added to a stirred ice-cooled solution of 276 g (2.06 mol) of l-chloro-3-hexanone (5)7 in 1 1. of dry ether.…”

Section: Methodsmentioning

confidence: 99%

“…The solvent was removed in vacuo; the residue was dissolved in chloroform and filtered through a small pad of Florisil. Concentration of the eluent afforded 75 mg of a mixture of trans-and ds-piperidones: nmr (100 MHz) (CDCls) 1.0 (t, J = 7 Hz), 1.81 (d of q, J = 7, 3 Hz), 2.1-3.8 (m), 4.45 (m), 5.16 (s), 5.6 (d, J = 6 Hz), 6.21 (s), 6.52 (d, 7 = 6 Hz), 6.95-8.0 (m), 8.15 (s), 8.34 (s), 8.58 (s), and 8.94 (broad d). Integration of the singlets at 5.16 and 6.21 and the doublets at 5.6 and 6.52 indicated a 70: 30 mixture of trans-cis.…”

Section: Methodsmentioning

confidence: 99%

“…Elution with 20% ethermethylene chloride yielded an oil which was crystallized from ether to give 180 mg (26%) of the trisubstituted unsaturated ketone 30. An analytical sample was recrystallized from ethyl acetate-cyclohexane: mp 160-162°; ir (CHC13) 3480, 1670,1640, and 1205 cm™1; uv max (95% EtOH) 219 (« 51,100), 273 (« 6100), 281 (« 6400), and 289 nm (e 5400); nmr (100 MHz) (CDC18) (t, 3, 7 = 8 Hz) 1.15-1.9 (m, 2), 2.35 (s, 3), 3.2-3.S (m, 2), 4.0 (d of d, 0.4,7 = 18,4 Hz), 4.82 (d of d, 0.6, 7 = 18, 4 Hz), 5.2 and 6.25 (2 s, 1), 6.78 (m, 1), 7.0 (m, 1), 7.2-7.9 (m, 4), 8.6 and 8.8 (2 s, 1, and 8.85 (broad s, 1); mass spectrum (70 eV) (relative intensity) 296 ( , 100), 172 (49).…”

Section: I'i MM Mmentioning

confidence: 99%

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Stereospecific syntheses of uleine and epiuleine

Buechi¹,

Gould²,

Naef³

1971

J. Am. Chem. Soc.

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1 -Aminohexan-3-one (12) prepared from the known 1 -chlorohexan-3-one (5) via the phthalimide 11 on Mannich condensation with 3-formylindole gave the trans-disubstituted piperidone 13. The stereochemistry of the corresponding formamide 15, which exists preferentially as a diaxially substituted piperidone, was established by nuclear magnetic resonance spectroscopy. Condensation of the ketone 15 with acetylene to the carbinol 21 was followed by treatment with mercuric acetate furnishing the acetoxy ketone 23. Reduction of the latter with lithium in liquid ammonia, cyclization of the resulting trans,trans-methyl ketone 24, and reduction of the formamide 29 with lithium aluminum hydride completed the stereospecific synthesis of epiuleine (3). The tetrasubstituted ,ßunsaturated ketone 31, available by pyrolysis of the acetate 23 on catalytic reduction, afforded mostly the cm,dimethyl ketone 35 in addition to minor portions of the cM./rozis-methyl ketone 37. Cyclization of the former with boron trifluoride followed by hydride reduction gave uleine (1). A reversal of the usual conformational stability relationship was encountered in several of the intermediates and attributed to the vicinal alkyl amide effect. Uleine, a secondary plant metabolite of Aspidosperma ulei Mgf., belongs to a small group of indole alkaloids whose structures lack the tryptamine unit. Work on the two-dimensional constitution of uleine was complete in 19592 but the configuration of the ethyl group remained to be established. The first evidence concerning this point was provided by the reaction of the alkaloid with methyl iodide. The high rate of quaternization observed suggested that the ethyl group is situated equatorially away from the basic nitrogen atom.3 An examination of Aspidosperma subincanum carried out in the same year led to the isolation of a new alkaloid which proved to be epiuleine.4 The C-methyl

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: I'i MM Mmentioning

confidence: 99%

See 1 more Smart Citation

Stereospecific syntheses of uleine and epiuleine

Buechi¹,

Gould²,

Naef³

1971

J. Am. Chem. Soc.

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“…The pathway to 6-oxosilicine (9A) is summarized in scheme 5. Two approaches to (=*=)-dasicarpidone and its 3-epimer have been published (78,79), and are summarized in scheme 6.…”

mentioning

confidence: 99%