Lactam &amp; amide acetals XXI. Use of pyroglutamic acid and proline in chiral synthesis of conformationally constrained piperazinones

Jain, Sanjay; Sujatha, Kodam; Krishna, K. V. R.; Roy, Raja; Singh, Jujhar; Anand, N.

doi:10.1016/s0040-4020(01)81592-1

Cited by 26 publications

(3 citation statements)

References 9 publications

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“…Calcd for C 27 H 27 N 3 O 2 (425.52): C,76.21;H,6.40;N,9.87. Found: C,76.19;H,6.33;N,9.62. ,73.82;H,6.42;N,9.22.…”

Section: (S)-(+)-2-mentioning

confidence: 99%

“…The starting methyl L-thiopyroglutamate 4 was prepared from L-glutamic acid following the procedure described in the literature. 9 The thiolactam 4 was subjected to sulfur extrusion reaction by following the literature procedure 10 to afford enaminones 5a-c in fair yields depending upon the electrophile chosen (Scheme 1, Table 1). The enaminones 5 exhibited the required spectral and analytical profiles.…”

Section: Figurementioning

confidence: 99%

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A Convenient Approach to the Synthesis of ω-Heterocyclic Amino Acids from Carboxy Lactams through Ring-Chain Transformation; Part 1: Synthesis of (2S)-/(2R)-2-Amino-4-(1-aryl-/1,5-diaryl-1H-pyrazol-3-yl)butyric Acid

Singh¹,

Sinha²,

Jain³

et al. 2005

Synthesis

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A general method is reported for the synthesis of w-heterocyclic a-amino acids, which involves preparation of enaminone intermediates from thiolactams, followed by reaction with dinucleophiles, resulting in a single-step condensation and ring-chain transformation to the desired w-heterocyclic a-amino acids after deprotection of amine and carboxylic group. The reaction steps preserve the chirality of the parent-substituted lactam. The method is illustrated by the synthesis of (2S)-and (2R)-2-amino-4-(1-aryl-/ 1,5-diaryl-1H-pyrazol-3-yl)butyric acids.

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“…Calcd for C 27 H 27 N 3 O 2 (425.52): C,76.21;H,6.40;N,9.87. Found: C,76.19;H,6.33;N,9.62. ,73.82;H,6.42;N,9.22.…”

Section: (S)-(+)-2-mentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

A Convenient Approach to the Synthesis of ω-Heterocyclic Amino Acids from Carboxy Lactams through Ring-Chain Transformation; Part 1: Synthesis of (2S)-/(2R)-2-Amino-4-(1-aryl-/1,5-diaryl-1H-pyrazol-3-yl)butyric Acid

Singh¹,

Sinha²,

Jain³

et al. 2005

Synthesis

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“…Reaction of nitromethane with thioimidate salts derived from pyroglutamate thiolactams provided the nitroenamines 464, which were reduced and cyclized to the conformationally restricted piperazines 465 112 (Scheme 90).…”

Section: C-5 Alkylationmentioning

confidence: 99%