A new method for the preparation of 3,4-dihydro - and 1,2,3,4-tetrahydro-.BETA.-carbolines.

Ishida, Akihiko; Nakamura, Tohru; Irie, Kunihiko; Oh-Ishi, T.

doi:10.1248/cpb.33.3237

Cited by 27 publications

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“…Optical rotations were measured with a JASCO DIP-370 polarimeter. Spectral data for compounds 4 , 7 , and 9 14 were identical to those previously reported.…”

Section: Methodssupporting

confidence: 70%

Enantiospecific Formation of Trans 1,3-Disubstituted Tetrahydro-β-carbolines by the Pictet−Spengler Reaction and Conversion of Cis Diastereomers into Their Trans Counterparts by Scission of the C-1/N-2 Bond

Cox¹,

Hamaker²,

Li³

et al. 1997

J. Org. Chem.

107

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The factors which effect the stereoselective formation of trans-1-alkyl-2-benzyl-3-(alkoxycarbonyl)-1,2,3,4-tetrahydro-beta-carbolines and trans-3-(alkoxycarbonyl)-1-alkyl-2-(diphenylmethyl)-1,2,3,4-tetrahydro-beta-carbolines by the Pictet-Spengler cyclization were examined by heating tryptophan derivatives with aldehydes of varied steric bulk under aprotic and acidic conditions, followed by determination of the ratio of cis to trans diastereomers so formed. The presence of a benzyl group at the N(b)-nitrogen atom alters the diastereochemical outcome of this condensation to provide 100% trans stereoselectivity when the cyclization is carried out with cyclohexanecarboxaldehyde. Furthermore, when N(b)-(diphenylmethyl)tryptophan isopropyl ester was condensed with aldehydes of any size, trans diastereomers are formed with 100% stereoselectively. The trans N(b)-substituted diastereomers are thermodynamically more stable than their cis congeners as shown by equilibration experiments in TFA. Conversion of the cis diastereomers into the more stable trans diastereomers is believed to occur under acidic conditions by cleavage of the carbon (C-1)-nitrogen (N-2) bond with complete retention of configuration at the C-3 stereocenter. Evidence from deuterium exchange experiments as well as optical rotations support this model for epimerization. In addition, when cis diastereomer 66a was allowed to stir in CF(3)COOD, the trans isomer 66b was isolated in 90% yield, while treatment of cis 66a with CF(3)COOH/NaBH(4) provided a mixture of the ring cleaved [scission across C(1)-N(2) bond] product 67 and the trans isomer 66b. Treatment of 66b (control experiment) with NaBH(4)/CF(3)COOH under the same conditions returned only starting trans 66b in excellent yield. The Pictet-Spengler reaction of substrates with sufficiently large substituents, followed by treatment with acid, permits the 100% enantiospecific formation of trans-1,3-disubstituted-1,2,3,4-tetrahydro-beta-carbolines for alkaloid total synthesis.

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“…Optical rotations were measured with a JASCO DIP-370 polarimeter. Spectral data for compounds 4 , 7 , and 9 14 were identical to those previously reported.…”

Section: Methodssupporting

confidence: 70%

Enantiospecific Formation of Trans 1,3-Disubstituted Tetrahydro-β-carbolines by the Pictet−Spengler Reaction and Conversion of Cis Diastereomers into Their Trans Counterparts by Scission of the C-1/N-2 Bond

Cox¹,

Hamaker²,

Li³

et al. 1997

J. Org. Chem.

107

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“…C NMR (101 MHz, CDCl 3 ) δ 174.0, 136.0, 134.6, 126.9, 121.9, 119.6, 118.0, 110.8, 62.6, 56.5, 52.3, 35.7, 27.1, 26.4. This compound has been previously reported and NMR data are consistent with literature 63.…”

supporting

confidence: 90%

Questioning the γ-gauche effect: stereoassignment of 1,3-disubstituted-tetrahydro-β-carbolines using¹H–¹H coupling constants

et al. 2019

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Polyphosphate Ester

Dixon¹

2001

Encyclopedia of Reagents for Organic Synthesis

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A new method for the preparation of 3,4-dihydro - and 1,2,3,4-tetrahydro-.BETA.-carbolines.

Cited by 27 publications

References 0 publications

Enantiospecific Formation of Trans 1,3-Disubstituted Tetrahydro-β-carbolines by the Pictet−Spengler Reaction and Conversion of Cis Diastereomers into Their Trans Counterparts by Scission of the C-1/N-2 Bond

Enantiospecific Formation of Trans 1,3-Disubstituted Tetrahydro-β-carbolines by the Pictet−Spengler Reaction and Conversion of Cis Diastereomers into Their Trans Counterparts by Scission of the C-1/N-2 Bond

Questioning the γ-gauche effect: stereoassignment of 1,3-disubstituted-tetrahydro-β-carbolines using¹H–¹H coupling constants

Polyphosphate Ester

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A new method for the preparation of 3,4-dihydro - and 1,2,3,4-tetrahydro-.BETA.-carbolines.

Cited by 27 publications

References 0 publications

Enantiospecific Formation of Trans 1,3-Disubstituted Tetrahydro-β-carbolines by the Pictet−Spengler Reaction and Conversion of Cis Diastereomers into Their Trans Counterparts by Scission of the C-1/N-2 Bond

Enantiospecific Formation of Trans 1,3-Disubstituted Tetrahydro-β-carbolines by the Pictet−Spengler Reaction and Conversion of Cis Diastereomers into Their Trans Counterparts by Scission of the C-1/N-2 Bond

Questioning the γ-gauche effect: stereoassignment of 1,3-disubstituted-tetrahydro-β-carbolines using1H–1H coupling constants

Polyphosphate Ester

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Questioning the γ-gauche effect: stereoassignment of 1,3-disubstituted-tetrahydro-β-carbolines using¹H–¹H coupling constants