The Aldol Addition Reaction

Heathcock, Clayton H.

doi:10.1016/b978-0-12-507703-3.50007-5

Cited by 244 publications

(90 citation statements)

References 143 publications

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“…The relative stereochemistry (C2/C3) of the products was determined using 1 H NMR and 13 C NMR spectroscopy, the vicinal constant coupling (J) for syn diastereoisomer varying between 5.9-6.32 Hz and 7-9 Hz for the anti isomer. 18 The results obtained in the hydrogenation step are summarized in Table 2. The preliminary observations indicate that there was a dependence on the size of the substituents directly bonded to the silicon atom and the diastereoselectivity.…”

Section: Resultsmentioning

confidence: 99%

“…18 Our previous results encouraged us to undertaken an additional study focused on determining the real influence of the protecting group on the diastereoselectivity of the heterogeneous catalytic hydrogenation with Baylis-Hillman adducts originating from both aliphatic and aromatic aldehydes. In this comunication we disclose the results we have obtained with this new study.…”

Section: Introductionmentioning

confidence: 99%

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The influence of protecting groups on the diastereoselectivity of catalytic heterogeneous hydrogenation of Baylis-Hillman adducts

Coelho¹,

Wanda²,

Almeida³

et al. 2003

Arkivoc

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In this communication we describe our recent results from a study on catalytic heterogeneous hydrogenation reactions of Baylis-Hillman adducts. Depending on the protecting groups used on the secondary hydroxyl group of these adducts, it is possible to obtain a high degree of diastereoselection. For silylated Baylis-Hillman adducts a high syn diastereoselectivity has been obtained. However, when secondary Baylis-Hillman hydroxyl groups were unprotected or protected as acetate a moderate anti selectivity was attained. The adducts protected as methyl ether gave poor syn diastereoselectivity.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The influence of protecting groups on the diastereoselectivity of catalytic heterogeneous hydrogenation of Baylis-Hillman adducts

Coelho¹,

Wanda²,

Almeida³

et al. 2003

Arkivoc

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“…Methylation of 65 followed by aldol condensation with the four carbon aldehyde 34 gave the wrong stereoisomer and eventually led to isoallocyathin B 2 (72) (Scheme 11). 35 After considerable experimentation, it was discovered that the desired diketone 75 could be prepared by methylation of diketone 74, the product of C-acylation of ketone 65. With key intermediate 85 in hand, the stage was set for the final expansion of ring C and installation of the required peripheral functionality (Scheme 15).…”

Section: Tori's Synthesismentioning

confidence: 99%

“…Subjecting 84 to samarium(II) iodide initiated a one carbon ring expansion 35 providing cycloheptanone 99. Sequential reduction and oxidation of 99 gave keto-aldehyde 100.…”

Section: Tori's Synthesismentioning

confidence: 99%

Enantioselective Total Synthesis of Cyathin A₃.

Ward

Shen

2007

ChemInform

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The cyathins are a unique group of diterpenoids produced by the bird's nest fungi Cyathus helenae, C. africanus, and C. earlei In Section 2.2, the enantioselective Diels-Alder reaction of quinone 106 and diene 105 is presented. This reaction is effectively catalyzed by a carefully iii prepared Mikami catalyst. It was carried out on a preparative scale to give the chiral building block 108. The absolute configuration of the Diels-Alder adduct 108 was determined by NMR and X-ray analysis.

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“…In fact, b-hydroxy ketones can serve as versatile building block for the asymmetric synthesis of carbohydrates, amino acids and many other biomolecules (4)(5)(6). They also provide privileged structural functionalities that exist in many important natural products (7)(8)(9)(10)(11)(12).…”

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The Mimic of Type II Aldolases Chemistry: Asymmetric Synthesis of β‐Hydroxy Ketones by Direct Aldol Reaction

Mei

Han

et al. 2010

Chem Biol Drug Des

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An efficient direct aldol reaction has been developed for the synthesis of chiral b-hydroxy ketone using a combination of C 1 -symmetric chiral prolinamides based on o-phenylenediamine and zinc triflate as catalyst. The reaction was convenient to carry out in aqueous media with up to 98% chemical yields and up to 94% ee values. The current strategy can be regarded as the analogue of aldolase type II, which suggests a new pathway for the designing of new organocatalysts. The development of stereoselective and enantioselective aldol reaction has become an interesting and challenging topic in modern organic and medicinal chemistry (1-3), because the resulting chiral b-hydroxy ketones belong to an extremely important class of biological compounds. In fact, b-hydroxy ketones can serve as versatile building block for the asymmetric synthesis of carbohydrates, amino acids and many other biomolecules (4-6). They also provide privileged structural functionalities that exist in many important natural products (7-12). For example, the b-hydroxy ketones functionalities exist in macrolide classes of antibiotics such as telithromycin and cethromycin which are targeted primarily against Gram-positive bacterial strains including Streptococcus pneumoniae and S. pyogenes, fastidious Gram-negative strains including Haemophilus influenzae and Moraxella catarrhalis, atypicals Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella pneumophilia (13). They were also found in conagenin that can improve the antitumor efficacy of adriamycin and mitomycin C against murine leukemias, which suggest its potential utility for cancer chemotherapy (14).In virtue of the importance of chiral b-hydroxy ketones, several approaches aiming to prepare them have been reported in the last decade (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). Among all the catalytic direct aldol, the most attractive one is the mimic of the actions of the enzymes. Although the direct catalytic aldol systems which were assumed to proceed through an enamine mechanism by mimic of aldolase type I have been well explored (28-32), the direct aldol systems by using the methods analogue to the actions of aldolase type II containing a zinc cofactor have still remained challenging. In fact, there were only a few reports for direct aldol reactions promoted by the zinc complexes with N-donor ligands in the presence of water until now (33-38). Herein, we reported a chiral ligands and zinc triflate catalyzed asymmetric direct aldol reaction with water as solvent. To our knowledge, this is the first example that mimics type II aldolase utilizing C 1 -symmetric organic molecular based on o-phenylenediamine as chiral ligand. Results and DiscussionsAccording to the mechanism of type II aldolase (33-38), we designed and prepared a series of chiral ligands (Figure 1). These chiral ligands 1-6 were easily prepared from proline and aniline or o-phenylenediamine in high yields. Most of these ligands have C 1 symmetry, expect compound 4, which is a C 2 -symmetric ligand. Then, all thes...

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The Aldol Addition Reaction

Cited by 244 publications

References 143 publications

The influence of protecting groups on the diastereoselectivity of catalytic heterogeneous hydrogenation of Baylis-Hillman adducts

The influence of protecting groups on the diastereoselectivity of catalytic heterogeneous hydrogenation of Baylis-Hillman adducts

Enantioselective Total Synthesis of Cyathin A₃.

The Mimic of Type II Aldolases Chemistry: Asymmetric Synthesis of β‐Hydroxy Ketones by Direct Aldol Reaction

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The Aldol Addition Reaction

Cited by 244 publications

References 143 publications

The influence of protecting groups on the diastereoselectivity of catalytic heterogeneous hydrogenation of Baylis-Hillman adducts

The influence of protecting groups on the diastereoselectivity of catalytic heterogeneous hydrogenation of Baylis-Hillman adducts

Enantioselective Total Synthesis of Cyathin A3.

The Mimic of Type II Aldolases Chemistry: Asymmetric Synthesis of β‐Hydroxy Ketones by Direct Aldol Reaction

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Enantioselective Total Synthesis of Cyathin A₃.