Base‐Induced Sequential Cyclization–Rearrangement of Enantioenriched 3‐Aminoalkanoates to Five‐ and Seven‐Membered Lactams

Sakai, Takeo; Yamada, Ken‐ichi; Tomioka, Kiyoshi

doi:10.1002/asia.200700423

Cited by 15 publications

(15 citation statements)

References 91 publications

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“…Abbreviations are as follows: s, singlet; d, doublet; t, triplet; m, multiplet; br, broad. 13 C peak multiplicity assignments were made based on DEPT data. IR spectroscopy of oil and solid samples were measured as neat liquid films and KBr pellets, respectively.…”

Section: Generalmentioning

confidence: 99%

“…N-Benzyltrimethylsilylamine, 10 2-trityloxyethylamine, 11 2a, 2 3, 12 5f, 13 and 6a 14 were prepared according to reported procedures.…”

Section: Starting Materialsmentioning

confidence: 99%

“…1 H and 13 C NMR, IR, and MS were identical to those reported. 13 4.5. The typical procedure A of Table 1 in 0.54 mmol scale using N- (2-p-methoxybenzyloxyethyl)…”

Section: 2 E N Tr Y 3 (! ) -Te R T-b U Ty L (S )-3 -B E N Z Y Lmentioning

confidence: 99%

“…(c 1.00, CHCl 3 ). 1 H NMR: 1.37 (9H, s), 1.65 (9H, s), 2.08 (1H, br s), 2.68-2.81 (4H, m), 3.50-3.56 (2H, m), 3.80 (3H, s), 4.38 (1H, dd, J = 6.3, 7.7), 4.42 (2H, s), 6.86 (2H, dd, J = 1.9, 8.3), 7.19-7.32 (4H, m), 7.52 (1H, s), 7.72 (1H, m), 8.15 (1H, m) 13. C NMR: 28.0 (CH 3 ), 28.2 (CH 3 ), 42.6 (CH 2 ), 47.1 (CH 2 ), 52.1 (CH 3 ), 55.2 (CH), 69.3 (CH 2 ), 72.6 (CH 2 ), 80.7 (C), 83.5 (C), 113.7 (CH), 115.2 (CH), 119.8 (CH), 121.9 (C), 122.4 (CH), 123.2 (CH), 124.3 (CH), 129.2 (C), 129.3 (CH), 130.4 (C), 135.8 (C), 149.7 (C), 159.1 (C), 171.1 (C).…”

mentioning

confidence: 99%

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Critical profiles of chiral diether-mediated asymmetric conjugate aminolithiation of enoate with lithium amide as a key to the total synthesis of (−)-kopsinine

Harada¹,

Sakai²,

Takasu³

et al. 2013

Tetrahedron

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Chiral diether-mediated asymmetric aminolithiation of indolylpropenoate with lithium amide in toluene at-78 °C for 15 min gave, after aqueous ammonium chloride quench, the corresponding conjugate addition product with 97% ee in 89% yield. If hydrogen chloride in methanol was selected as a quencher, however, aminolithiation at-78 °C for 3 h gave the corresponding adduct with 97% ee in 54% yield, along with recovery of the starting enoate in 39% yield. Based on this finding of an incomplete and slow reaction at !78 °C, the aminolithiation conditions were optimized to be at !60 °C for 15 h and subsequent enolate trap with alkyl halide upon an addition of DMPU afforded the desired aminoalkylation product with 98% ee in 89% yield. Further approach towards total synthesis of (-)-kopsinine was carried out by examining asymmetric aminoithiation with N-hydroxyethylamine equivalent, one-pot piperidine formation, and Claisen condensation.

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Section: Generalmentioning

confidence: 99%

“…N-Benzyltrimethylsilylamine, 10 2-trityloxyethylamine, 11 2a, 2 3, 12 5f, 13 and 6a 14 were prepared according to reported procedures.…”

Section: Starting Materialsmentioning

confidence: 99%

“…1 H and 13 C NMR, IR, and MS were identical to those reported. 13 4.5. The typical procedure A of Table 1 in 0.54 mmol scale using N- (2-p-methoxybenzyloxyethyl)…”

Section: 2 E N Tr Y 3 (! ) -Te R T-b U Ty L (S )-3 -B E N Z Y Lmentioning

confidence: 99%

mentioning

confidence: 99%

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Critical profiles of chiral diether-mediated asymmetric conjugate aminolithiation of enoate with lithium amide as a key to the total synthesis of (−)-kopsinine

Harada¹,

Sakai²,

Takasu³

et al. 2013

Tetrahedron

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“…It is noteworthy that the formation of seven-membered lactam 20 is highly selective for cis while that of 5-membered lactam is trans selective. Two-step asymmetric and diastereoselective synthesis of enantiomerically enriched seven-membered lactam 17 is the highlight of this process [11].…”

Section: One-pot Stereoselective Conversion Of 3-aminocarboxylates Tomentioning

confidence: 99%

Aminolithiation of carbon-carbon double bonds as a powerful tool in organic synthesis

Tomioka

Sakai

Ogata

et al. 2009

Pure and Applied Chemistry

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A conjugate amination of α,β-unsaturated carbonyl compounds with lithium amides has become a powerful method of N-C bond-forming reactions. Chiral ligand-controlled asymmetric version of the conjugate amination of enoates was developed for practical bench chemistry, giving the enantioenriched amination product with over 99 % ee. In situ diastereoselective alkylation of resulting lithium enolates allowed us to form vicinal N-C and C-C bonds in a one-pot operation. This protocol enabled us to realize a short-step asymmetric synthesis of otamixaban key intermediate. Treatment of product 3-benzylamino-and 3-allylaminoesters with tert-butyllithium gave five-or seven-membered lactams through [1,2]-or [2,3]-rearrangement of intermediate β-lactams. Isolated C-C double bonds were also found to accept intramolecular aminolithiation affording the corresponding hydroamination products. Chiral lithiophilic ligand-catalyzed reaction gave enantioenriched hydroamination products with high ee. Stereoselective intramolecular aminolithiation of allylaminoalkenes was coupled with subsequent carbolithiation to give doubly cyclized product amines.

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ChemInform Abstract: Base‐Induced Sequential Cyclization—Rearrangement of Enantioenriched 3‐Aminoalkanoates to Five‐ and Seven‐Membered Lactams.

2008

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Pyrrole derivatives R 0120Base-Induced Sequential Cyclization-Rearrangement of Enantioenriched 3-Aminoalkanoates to Five-and Seven-MemberedLactams. -Chirality at the α-position of the ester group can be transferred to the cyclization-rearrangement product. -(SAKAI, T.; YAMADA, K.-I.; TOMIOKA*, K.; Chem. Asian J. 3 (2008) 8-9, 1486-1493; Grad. Sch. Pharm. Sci., Kyoto Univ., Sakyo, Kyoto 606, Japan; Eng.) -Nuesgen 51-113

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Base‐Induced Sequential Cyclization–Rearrangement of Enantioenriched 3‐Aminoalkanoates to Five‐ and Seven‐Membered Lactams

Cited by 15 publications

References 91 publications

Critical profiles of chiral diether-mediated asymmetric conjugate aminolithiation of enoate with lithium amide as a key to the total synthesis of (−)-kopsinine

Critical profiles of chiral diether-mediated asymmetric conjugate aminolithiation of enoate with lithium amide as a key to the total synthesis of (−)-kopsinine

Aminolithiation of carbon-carbon double bonds as a powerful tool in organic synthesis

ChemInform Abstract: Base‐Induced Sequential Cyclization—Rearrangement of Enantioenriched 3‐Aminoalkanoates to Five‐ and Seven‐Membered Lactams.

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