A New Chiral BLA Promoter for Asymmetric Aza Diels-Alder and Aldol-Type Reactions of Imines

Ishihara, Kazuaki; Miyata, Mayumi; Hattori, Kouji; Tada, Toshiji; Yamamoto, Hisashi

doi:10.1021/ja00102a019

Cited by 214 publications

(94 citation statements)

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“…The reactions open useful ways to chiral ␤-amino ketones or esters (Mannich bases), which are versatile chiral building blocks for the synthesis of many nitrogen-containing, biologically important compounds including ␤-amino acids, ␤-lactams, etc. Compared with asymmetric Mannich-type reactions using stoichiometric amounts of chiral sources (13)(14)(15)(16), little is known concerning catalytic asymmetric versions. In 1997, we reported an example of truly catalytic enantioselective Mannich-type reactions of imines with silicon enolates by using a zirconium catalyst prepared from zirconium (9).…”

Section: Resultsmentioning

confidence: 99%

Air-stable, storable, and highly efficient chiral zirconium catalysts for enantioselective Mannich-type, aza Diels–Alder, aldol, and hetero Diels–Alder reactions

Kobayashi

Ueno

Saitō

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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For the synthesis of optically active compounds, chiral catalysts have attracted much attention because large quantities of optically active molecules can be prepared from a small amount of a chiral source. However, many chiral catalysts are often unstable in air (oxygen) and͞or in the presence of water. This is especially the case in chiral Lewis acid catalysis, because most Lewis acids are air-and moisture-sensitive. Therefore, many catalysts are prepared in situ in an appropriate solvent just before use, and they cannot be stored for extended periods. We have developed air-stable, storable, and highly efficient chiral zirconium Lewis acids. The catalysts promoted asymmetric Mannich-type, aza Diels-Alder, aldol, and hetero Diels-Alder reactions efficiently with high enantioselectivities. A key to stabilizing the catalysts is an appropriate combination of chiral zirconium Lewis acids with molecular sieves, and the zirconium-molecular sieves-combined catalysts can be stored for extended periods in air at room temperature without loss of activity. Moreover, it has been demonstrated that the catalysts can be recovered and reused.

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Section: Resultsmentioning

confidence: 99%

Air-stable, storable, and highly efficient chiral zirconium catalysts for enantioselective Mannich-type, aza Diels–Alder, aldol, and hetero Diels–Alder reactions

Kobayashi

Ueno

Saitō

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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“…24 The direct catalytic asymmetric Mannich reaction using unmodified ketones was reported using cooperactive catalysis of a AlLibis((R)-binaphtoxide) complex [(R)-ALB] and La(OTf) 3 nH 2 O. 25 It was also reported that enantioselective and diastereoselective catalytic nitro-Mannich reactions of N-phosphinoylimines proceeded smoothly using a complex consisting of ALB and tert-BuOK.…”

Section: Direct Reactionsmentioning

confidence: 99%

“…2 Ishihara et al disclosed enantioselective reactions of achiral imines with an achiral ketene silyl acetal using a Brønsted acid-assisted chiral Lewis acid. 3 In both cases, however, stoichiometric amounts of chiral sources were needed. Enantioselective Mannich reactions using small amounts of chiral sources have not been reported before 1997.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Enantioselective Mannich Reactions

Ueno

Kobayashi

2005

Enantioselective Synthesis of Β-Amino Acids

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“…[37][38][39][40][41] In the course of our studies on remote asymmetric induction using chiral sulfoxides, we previously reported the lanthanoid triflate-catalyzed Mukaiyama aldol reaction of sulfinyl aldehyde 1 with silyl ketene acetals.…”

mentioning

confidence: 99%

“…[12][13][14] Chiral versions of these condensations have also been devised by the use of imines with a chiral auxiliary, [1][2][3][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] chiral ester enolate derivatives, [30][31][32][33][34][35][36] and chiral Lewis acids. [37][38][39][40][41] In the course of our studies on remote asymmetric induction using chiral sulfoxides, we previously reported the lanthanoid triflate-catalyzed Mukaiyama aldol reaction of sulfinyl aldehyde 1 with silyl ketene acetals. 42) Highly remote stereocontrol of 1 in this reaction led us to examine an enantioselective route to b-lactams by diastereoselective condensation of an aldimine 2 derived from 1 with silyl ketene acetals as well as enolates.…”

mentioning

confidence: 99%

Diastereoselective Imino-Aldol Condensation of Chiral 3-(p-Tolylsulfinyl)-2-furaldimine and Ester Enolates.

Arai

Yoneda

Masuda

et al. 2002

CHEMICAL & PHARMACEUTICAL BULLETIN

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The biological importance of b-lactams as antibiotics has stimulated the development of efficient procedures for the preparation of this class of compounds. Of the synthetic routes to b-lactams that have been reported, Lewis acid-promoted [1][2][3] and catalyzed [4][5][6][7][8][9][10][11] condensations of imines with silyl ketene acetals and imino-aldol condensations with ester enolates are powerful methods which involve the efficient construction of stereogenic centers of the b-lactam moiety.12-14) Chiral versions of these condensations have also been devised by the use of imines with a chiral auxiliary, [1][2][3][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] chiral ester enolate derivatives, [30][31][32][33][34][35][36] and chiral Lewis acids. [37][38][39][40][41] In the course of our studies on remote asymmetric induction using chiral sulfoxides, we previously reported the lanthanoid triflate-catalyzed Mukaiyama aldol reaction of sulfinyl aldehyde 1 with silyl ketene acetals.42) Highly remote stereocontrol of 1 in this reaction led us to examine an enantioselective route to b-lactams by diastereoselective condensation of an aldimine 2 derived from 1 with silyl ketene acetals as well as enolates. We would like to report the details of this condensation using the sulfinyl furaldimine 2. 43)Initial experiments were performed with a typical silyl ketene acetal 3a in the presence of a lanthanoid triflate, which is found to be effective for the aldol condensation of the aldehyde 1. 42) In fact, the reaction using Yb(OTf) 3 proceeded smoothly; diastereoisomeric b-amino esters 4a and 6a were produced in a ratio of 1 : 1 (Table 1, entry 1).44) The use of other lanthanoid triflates did not improve the diastereoselectivity. The relative stereochemistry of the two products 4a and 6a was not determined at this stage; however, the configuration at the C(3) position was later determined (vide infra). We then turned our attention to using an ester enolate

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A New Chiral BLA Promoter for Asymmetric Aza Diels-Alder and Aldol-Type Reactions of Imines

Cited by 214 publications

References 0 publications

Air-stable, storable, and highly efficient chiral zirconium catalysts for enantioselective Mannich-type, aza Diels–Alder, aldol, and hetero Diels–Alder reactions

Air-stable, storable, and highly efficient chiral zirconium catalysts for enantioselective Mannich-type, aza Diels–Alder, aldol, and hetero Diels–Alder reactions

Catalytic Enantioselective Mannich Reactions

Diastereoselective Imino-Aldol Condensation of Chiral 3-(p-Tolylsulfinyl)-2-furaldimine and Ester Enolates.

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