Diastereoselective electrophilic α-amination of camphor N1-acyl N2-phenylpyrazolidinones: the metal enolate-dependent synthesis of two possible hydrazide diastereomers

Chin Sheng Chao; Chung Kai Cheng; Ssu Hsien Li; Kwunmin Chen

doi:10.1016/j.tetlet.2008.11.003

Diastereoselective electrophilic α-amination of camphor N¹-acyl N²-phenylpyrazolidinones: the metal enolate-dependent synthesis of two possible hydrazide diastereomers

Chin Sheng Chao, Chung Kai Cheng, Ssu Hsien Li, Kwunmin Chen

Department of Chemistry

Research output: Contribution to journal › Article › peer-review

11 Citations (Scopus)

Abstract

Complementary approaches under enolate amination reactions for the synthesis of both α-hydrazidoacyl diastereomers have been achieved. Both isomers are obtained with high to excellent chemical yields and high stereoselectivities (up to >95:5 dr) when aryl-substituted camphor N¹-acyl N²-phenylpyrazolidinone was treated with potassium hexamethyldisilylamide (KHMDS) and lithium hexamethyldisilylamide (LHMDS), respectively, followed by the addition of di-tert-butyl azodicarboxylate. The nondestructive removal of the chiral auxiliary, which can be carried out under mild condition, afforded the hydrazido alcohol with high enantiomeric ratio. The facial stereoselectivity and stereochemical course of the reactions are discussed.

Original language	English
Pages (from-to)	333-336
Number of pages	4
Journal	Tetrahedron Letters
Volume	50
Issue number	3
DOIs	https://doi.org/10.1016/j.tetlet.2008.11.003
Publication status	Published - 2009 Jan 21

Keywords

Amination
Chiral auxiliary
Reversal of stereoselectivity

ASJC Scopus subject areas

Biochemistry
Drug Discovery
Organic Chemistry

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Diastereoselective electrophilic α-amination of camphor N¹-acyl N²-phenylpyrazolidinones : the metal enolate-dependent synthesis of two possible hydrazide diastereomers. / Chao, Chin Sheng; Cheng, Chung Kai; Li, Ssu Hsien; Chen, Kwunmin.

In: Tetrahedron Letters, Vol. 50, No. 3, 21.01.2009, p. 333-336.

Research output: Contribution to journal › Article › peer-review

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abstract = "Complementary approaches under enolate amination reactions for the synthesis of both α-hydrazidoacyl diastereomers have been achieved. Both isomers are obtained with high to excellent chemical yields and high stereoselectivities (up to >95:5 dr) when aryl-substituted camphor N1-acyl N2-phenylpyrazolidinone was treated with potassium hexamethyldisilylamide (KHMDS) and lithium hexamethyldisilylamide (LHMDS), respectively, followed by the addition of di-tert-butyl azodicarboxylate. The nondestructive removal of the chiral auxiliary, which can be carried out under mild condition, afforded the hydrazido alcohol with high enantiomeric ratio. The facial stereoselectivity and stereochemical course of the reactions are discussed.",

keywords = "Amination, Chiral auxiliary, Reversal of stereoselectivity",

author = "Chao, {Chin Sheng} and Cheng, {Chung Kai} and Li, {Ssu Hsien} and Kwunmin Chen",

note = "Funding Information: This work was supported by the National Science Council of the Republic of China (NSC 96-2113-M-003-005-MY3) and the National Taiwan Normal University (96TOP001). Our gratitude goes to the Academic Paper Editing Clinic, NTNU, and we are also grateful to the National Center for High-Performance Computing for computer time and facilities. ",

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AU - Cheng, Chung Kai

AU - Li, Ssu Hsien

AU - Chen, Kwunmin

N1 - Funding Information: This work was supported by the National Science Council of the Republic of China (NSC 96-2113-M-003-005-MY3) and the National Taiwan Normal University (96TOP001). Our gratitude goes to the Academic Paper Editing Clinic, NTNU, and we are also grateful to the National Center for High-Performance Computing for computer time and facilities.

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N2 - Complementary approaches under enolate amination reactions for the synthesis of both α-hydrazidoacyl diastereomers have been achieved. Both isomers are obtained with high to excellent chemical yields and high stereoselectivities (up to >95:5 dr) when aryl-substituted camphor N1-acyl N2-phenylpyrazolidinone was treated with potassium hexamethyldisilylamide (KHMDS) and lithium hexamethyldisilylamide (LHMDS), respectively, followed by the addition of di-tert-butyl azodicarboxylate. The nondestructive removal of the chiral auxiliary, which can be carried out under mild condition, afforded the hydrazido alcohol with high enantiomeric ratio. The facial stereoselectivity and stereochemical course of the reactions are discussed.

AB - Complementary approaches under enolate amination reactions for the synthesis of both α-hydrazidoacyl diastereomers have been achieved. Both isomers are obtained with high to excellent chemical yields and high stereoselectivities (up to >95:5 dr) when aryl-substituted camphor N1-acyl N2-phenylpyrazolidinone was treated with potassium hexamethyldisilylamide (KHMDS) and lithium hexamethyldisilylamide (LHMDS), respectively, followed by the addition of di-tert-butyl azodicarboxylate. The nondestructive removal of the chiral auxiliary, which can be carried out under mild condition, afforded the hydrazido alcohol with high enantiomeric ratio. The facial stereoselectivity and stereochemical course of the reactions are discussed.

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KW - Reversal of stereoselectivity

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