Asymmetric hetero Diels-Alder reaction catalyzed by stable and easily prepared chiral (acyloxy)borane (CAB) catalysts

Gao, Qingzhi; Maruyama, Tadashi; Mouri, Makoto; Yamamoto, Hisashi

doi:10.1021/jo00033a005

Cited by 79 publications

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“…Complex and sensitive molecules give high yields of products with few side reactions, testimony to the mildness of these catalysts (1)(2)(3). Asymmetric versions of the latter type of Diels-Alder reactions have been limited to only a few isolated examples (4)(5)(6) with little success in the cycloaddition of vinyl ethers to a,P-unsaturated aldehydes (3). All of the lanthanide complexes tried as catalysts were in fact either NMR shift reagents or commercially available complexes designed for other uses (1-3).…”

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confidence: 99%

Novel, air-stable, lanthanide catalysts for the hetero Diels–Alder reaction

Spino¹,

Clouston²,

Berg³

1996

Can. J. Chem.

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Novel, air-stable, yttrium and ytterbium complexes were found effective in the catalysis of the typical hetero DielsAlder reaction of crotonaldehyde and ethylvinyl ether. They represent an attractive solution to the problem of ligand lability in the realm of lanthanide catalysts.Key words: lanthanide, catalyst, hetero Diels-Alder, yttrium, ytterbium.RCsumC : Deux nouveaux complexes d'yttrium et d'ytterbium, stable a l'air, se sont avCrCs trks efficace comme catalyseurs d'une rkaction typique de Diels-Alder hCtCro impliquant la crotonaldChyde et 1'Cther d'ethylevinyle. 11s repkentent une solution attrayante au problkme chronique de la labilitC des ligands chez les catalyseurs de lanthanide.Mots clis : lanthanide, catalyseur, Diels-Alder hCtCro, yttrium, ytterbium. I ILanthanides are increasingly used in organic synthesis as mild I reagents and catalysts that can spare many sensitive functional groups (1 and, for reviews, 2). Catalytic systems based on lan-I thanide metals have been found for many organic reactions, ~ including the Friedel-Crafts reaction, acetal and ether formation, reduction and oxidation, and the Diels-Alder cycloaddi-I tion or, more particularly, the hetero Diels-Alder reaction I involving an oxygen on the dienophile or diene (1, 3). Complex and sensitive molecules give high yields of products with few side reactions, testimony to the mildness of these catalysts (1-3). Asymmetric versions of the latter type of Diels-Alder reactions have been limited to only a few isolated examples (4-6) with little success in the cycloaddition of vinyl ethers to a,P-unsaturated aldehydes (3). All of the lanthanide complexes tried as catalysts were in fact either NMR shift reagents or commercially available complexes designed for other uses (1-3). Part of the obstacle to achieving high asymmetric induction with lanthanide catalysts can be attributed to the lability of the ligands around the metal. In reality, this lability confers a degree of uncertainty about the actual structure of the active catalyst. In addition, it may impair induction because of ligand displacement during catalysis. We felt that a necessary step in designing efficient lanthanide catalysts for that reaction was to find suitable ligands with low lability and to make complexes of a well-defined structure. Only then could we rationally design chiral complexes with the hope of increasing the enantioselectivities so far achieved with lanthanide systems. We describe herein our success in synthesizing two novel, air-stable, and effective yttrium and ytterbium complexes that show low ligand lability and are efficient catalysts for the hetero Diels-Alder reaction. To the best of our knowledge, these are the first examples of well-defined hexadentate2 ligand-metal complexes of a lanthanide or yttrium that are effective catalysts.3 Their stability in air is a good indicator of low ligand lability and we believe they are strong forerunners of chiral complexes.The rationale for using tripodal ligands was to contribute extra stability to the c...

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confidence: 99%

Novel, air-stable, lanthanide catalysts for the hetero Diels–Alder reaction

Spino¹,

Clouston²,

Berg³

1996

Can. J. Chem.

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“…The chiral acyloxyborane (CAB) catalyst 4 derived from O-[2,6-di(isopropoxy)benzoyl]-L-tartaric acid and 2-methoxyphenylboronic acid also catalyzes the reaction of Danishefsky-type diene 5 with aldehydes to give the hetero-Diels-Alder adducts 6 with high enantioselectivities. 15 Chiral chromium(III) complexes, such as 7 (X¼ BF 4 , Cl) and 8 (X¼Cl, SbF 6 ) (Figure 1), are highly efficient catalysts for the hetero-Diels-Alder reactions of Danishefsky-type dienes 9 with unactivated aldehydes. [16][17][18] The chiral salen-chromium(III) complex 7 (X¼ BF 4 ) catalyzes the hetero-Diels-Alder reaction of 1 with various aldehydes to give the corresponding cyclohexenones with high enantioselectivity (equation 1, Table 1).…”

Section: Oxo-diels-alder Reactionsmentioning

confidence: 99%

5.10 Hetero-Diels–Alder Reactions

Ishihara¹,

Sakakura²

2014

Comprehensive Organic Synthesis II

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“…The cycloaddition reaction of conjugated dienes with carbonyl compounds, known as the hetero-Diels-Alder reaction, has been, since its discovery, one of the cornerstone reactions in organic synthesis for the construction of sixmembered rings containing an oxygen atom [7][8][9][10][11]. In this article, we are aimed to prepare N-acylated derivatives from the reaction of metacryloyl chloride and heterocyclic amines or organic amines then used in the synthesis of heterocyclic compounds.…”

Section: Introductionmentioning

confidence: 99%

An unexpected tandem cycloaddition reaction of α,β-unsaturated acid chloride with amines: Synthesis of dihydropyrancarboxamide derivatives and biological activity

Elassar

2015

Eur. J. Chem.

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Asymmetric hetero Diels-Alder reaction catalyzed by stable and easily prepared chiral (acyloxy)borane (CAB) catalysts

Cited by 79 publications

References 0 publications

Novel, air-stable, lanthanide catalysts for the hetero Diels–Alder reaction

Novel, air-stable, lanthanide catalysts for the hetero Diels–Alder reaction

5.10 Hetero-Diels–Alder Reactions

An unexpected tandem cycloaddition reaction of α,β-unsaturated acid chloride with amines: Synthesis of dihydropyrancarboxamide derivatives and biological activity

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