Stereocontrolled preparation of 1,2-diol with quaternary chiral center

Murata, Yoshihisa; Kamino, Tomoyuki; Hosokawa, Seijiro; Kobayashi, Susumu

doi:10.1016/s0040-4039(02)01946-9

Cited by 35 publications

(24 citation statements)

References 5 publications

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“…Thus, the synthesis of pyrrolidine 4 began with an asymmetric aldol reaction [7] between benzyloxybutyraldehyde (9) and Evans' auxiliary-appended amide 10 by using Ti(OiPr) 3 -Cl and ethyldiisopropylamine (DIPEA) to result in aldol adduct 6 in 83 % yield and approximately a dr of 95:5 [8] (Scheme 2). [9] This reaction allowed us to install the tertiary asymmetric carbon atom with the required stereochemistry.…”

Section: Resultsmentioning

confidence: 99%

Towards Allopumiliotoxins: A Concise Synthesis of the Indolizidine Core

2011

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Section: Resultsmentioning

confidence: 99%

Towards Allopumiliotoxins: A Concise Synthesis of the Indolizidine Core

2011

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“…Good to moderate stereoselectivities were obtained, depending on the stereochemistry of the enolates (Table 3.3). 55 Kobayashi et al [18,19] investigated the stereochemistry of the aldol addition of lactate derivatives and found a remarkable improvement in the anti-selectivity when titanium enolates were employed (Scheme 3.8, Table 3.4).…”

Section: Titanium and Zirconium Enolatesmentioning

confidence: 99%

Aldol Reactions

Schetter

Mahrwald

2005

Quaternary Stereocenters

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IntroductionThe aldol reaction and the related Claisen reaction are some of the most powerful methods for carbon-carbon bond formation [1]. Particularly since the mid-1980s, intensive research in this field has generated several new routes to stereo-and regiocontrol [2] as well as new catalytic reaction types. Although, overall, many variations of these reactions exist, only a few of them are generally applicable pathways for the creation of quaternary carbon centers.Formally, there exist two main reaction types to create a quaternary stereocenter via aldol additions (and related reactions). The first pathway is the addition of a carbonyl compound 1 (or a correspondding activated species) with two different -substituents (R 2 R 3 ) to another carbonyl compound 2. This method generates a quaternary carbon atom next to the carbonyl group of the aldols 3 and 4 (Scheme 3.1).The second pathway (Scheme 3.2) is the aldol addition of an enolizable carbonyl compound 5 to a carbonyl function 6 with two different substituents (R 2 R 3 ), which creates an aldol 7 with an asymmetric tertiary alcohol. Scheme 3.1 Scheme 3.2 Quaternary Stereocenters: Challenges and Solutions for Organic Synthesis. Edited

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“…We initially selected a titanium Lewis acid as we thought the titanium enolate would best facilitate the coordination of the aldehyde via the Zimmerman-Traxler transition state (see Table 1). 18,19 A similar strategy has been employed previously by the Kobayashi group in which LDA was used in combination with TiCl(O- i -Pr) 3 to form the titanium enolate in preparation of a 1,2-diol with a quaternary chiral center. 19 …”

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“…18,19 A similar strategy has been employed previously by the Kobayashi group in which LDA was used in combination with TiCl(O- i -Pr) 3 to form the titanium enolate in preparation of a 1,2-diol with a quaternary chiral center. 19 …”

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“…The configuration of the β-alcohol in this intermediate was confirmed as R by Mosher’s analysis, which was consistent with the predicted Zimmerman-Traxler transition state model. 19 The Evans’ chiral auxiliary was removed via hydrolysis to furnish (3 R )- 2 with an overall yield of 29%. The synthesis was also conducted starting with ( S )-4-benzyl-2-oxazolidinone.…”

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Expedient synthesis of α,α-dimethyl-β-hydroxy carbonyl scaffolds via Evans’ aldol reaction with a tertiary enolate

Nunnery

Suyama

Linington

et al. 2011

Tetrahedron Letters

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An efficient synthetic methodology for 3-hydroxy-2,2-dimethyloctynoic acid (DHOYA) and several variants, which are increasingly common fragments encountered in bioactive marine cyanobacterial metabolites, was developed. These fragments were obtained in three steps via a tertiary aldol reaction utilizing an Evans’ chiral auxiliary to afford the desired stereochemistry at the β-hydroxy carbon. Thus far, this methodology has been successfully applied in determination of the absolute stereochemistry of eight cyanobacterial natural products, including the VGSC activator palymramide A.

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Stereocontrolled preparation of 1,2-diol with quaternary chiral center

Cited by 35 publications

References 5 publications

Towards Allopumiliotoxins: A Concise Synthesis of the Indolizidine Core

Towards Allopumiliotoxins: A Concise Synthesis of the Indolizidine Core

Aldol Reactions

Expedient synthesis of α,α-dimethyl-β-hydroxy carbonyl scaffolds via Evans’ aldol reaction with a tertiary enolate

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