Mercuric acetate cyclization of -(arylmethyl)piperidines; synthesis of indolo [,-g]morphans (tetracyclic ring system of strychnos indole alkaloids) and ,-benzomorphans

Bosch, Joan; Bonjoch, Josep; Diez, Anna; Linares, A.; Moral, Montserrat; Rubiralta, Mario

doi:10.1016/s0040-4020(01)96488-9

Cited by 23 publications

(8 citation statements)

References 49 publications

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“…The intermediate N ‐acyl iminium ion 14 underwent cyclization to yield the tricyclic benzazocinones 15 (Scheme ). Thus, this synthesis provided 7,8‐benzomorphans 15 in high yields and is a significant improvement over previous syntheses of the tricyclic core via N ‐acyl iminium species 13c,d. 14 The electrophilic attack at the phenyl ring occurred exclusively from the cis side.…”

Section: Methodsmentioning

confidence: 84%

Broadening Deoxysugar Glycodiversity: Natural and Engineered Transaldolases Unlock a Complementary Substrate Space

Rale

Schneider

Sprenger

et al. 2011

Chemistry A European J

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The majority of prokaryotic drugs are produced in glycosylated form, with the deoxygenation level in the sugar moiety having a profound influence on the drug's bioprofile. Chemical deoxygenation is challenging due to the need for tedious protective group manipulations. For a direct biocatalytic de novo generation of deoxysugars by carboligation, with regiocontrol over deoxygenation sites determined by the choice of enzyme and aldol components, we have investigated the substrate scope of the F178Y mutant of transaldolase B, TalB(F178Y), and fructose 6-phosphate aldolase, FSA, from E. coli against a panel of variously deoxygenated aldehydes and ketones as aldol acceptors and donors, respectively. Independent of substrate structure, both enzymes catalyze a stereospecific carboligation resulting in the D-threo configuration. In combination, these enzymes have allowed the preparation of a total of 22 out of 24 deoxygenated ketose-type products, many of which are inaccessible by available enzymes, from a [3×8] substrate matrix. Although aliphatic and hydroxylated aliphatic aldehydes were good substrates, D-lactaldehyde was found to be an inhibitor possibly as a consequence of inactive substrate binding to the catalytic Lys residue. A 1-hydroxy-2-alkanone moiety was identified as a common requirement for the donor substrate, whereas propanone and butanone were inactive. For reactions involving dihydroxypropanone, TalB(F178Y) proved to be the superior catalyst, whereas for reactions involving 1-hydroxybutanone, FSA is the only choice; for conversions using hydroxypropanone, both TalB(F178Y) and FSA are suitable. Structure-guided mutagenesis of Ser176 to Ala in the distant binding pocket of TalB(F178Y), in analogy with the FSA active site, further improved the acceptance of hydroxypropanone. Together, these catalysts are valuable new entries to an expanding toolbox of biocatalytic carboligation and complement each other well in their addressable constitutional space for the stereospecific preparation of deoxysugars.

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Section: Methodsmentioning

confidence: 84%

Broadening Deoxysugar Glycodiversity: Natural and Engineered Transaldolases Unlock a Complementary Substrate Space

Rale

Schneider

Sprenger

et al. 2011

Chemistry A European J

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“…This regioselectivity stems from the Markovnikov additions of hydroxamic acids to the gold-activated terminal alkynes. In contrast, with corresponding methyl ketones as substrates in the Fischer indole synthesis, strongly acidic mediums (e.g., 5 % P 2 O 5 /neat MsOH 13 or neat PPA 14 ) are necessary to favor 2-alkylindoles with low to moderate regioselectivities.…”

mentioning

confidence: 99%

Au-catalyzed synthesis of 2-alkylindoles from N-arylhydroxylamines and terminal alkynes

2011

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“…After being stirred for 30 min, the solution was extracted with chloroform. The extract was washed with water, dried, and evaporated to yield the amino acetal (5) (8).-A solution of the amino acetal (5) (22 g, 0.16 mol) and 3methoxybenzaldehyde (19 g, 0.14 mol) in anhydrous benzene (350 cm3) was stirred at 0 "C for 30 min, at room temperature for 1 h, and under reflux for 4 h. After additional reflux with removal of water by a Dean-Stark trap (16 h), the solvent was evaporated off to give the imine (8) 9). -PTSA monohydrate (22.6 g, 0.12 mol) was added to a solution of 2,3,4-trimethoxybenzaldehyde (23.1 g, 0.12 mol) in an anhydrous mixture of benzene (100 cm3) and toluene (100 cm3).…”

Section: -Phthalimidobutan-2-one Ethjplene Acetal (4)mentioning

confidence: 99%

Benzomorphan-related compounds. Part 21. Synthesis of 7,8-benzomorphans via 2-aryl-4-piperidones

Bosch¹,

Rubiralta²,

Moral³

et al. 1986

J. Chem. Soc., Perkin Trans. 1

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Mercuric acetate cyclization of -(arylmethyl)piperidines; synthesis of indolo [,-g]morphans (tetracyclic ring system of strychnos indole alkaloids) and ,-benzomorphans

Cited by 23 publications

References 49 publications

Broadening Deoxysugar Glycodiversity: Natural and Engineered Transaldolases Unlock a Complementary Substrate Space

Broadening Deoxysugar Glycodiversity: Natural and Engineered Transaldolases Unlock a Complementary Substrate Space

Au-catalyzed synthesis of 2-alkylindoles from N-arylhydroxylamines and terminal alkynes

Benzomorphan-related compounds. Part 21. Synthesis of 7,8-benzomorphans via 2-aryl-4-piperidones

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