Chiral rare earth organophosphates as homogeneous Lewis acid catalysts for the highly enantioselective hetero-Diels–Alder reactions

Furuno, Hiroshi; Hayano, Tetsuji; Kambara, Takeshi; Sugimoto, Yuichi; Hanamoto, Takeshi; Tanaka, Yumiko; Jin, Yong Zhi; Kagawa, Takumi; Inanaga, Junji

doi:10.1016/j.tet.2003.06.011

Cited by 65 publications

(20 citation statements)

References 68 publications

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“…Inanaga and co-workers [103][104][105] observed a remarkably high (+)-NLE in the lanthanide-catalyzed (119) heteroDiels-Alder reaction shown in Equation (32). It was the first example of an ML 3 system.…”

Section: Diels-alder Reactionsmentioning

confidence: 95%

Nonlinear Effects in Asymmetric Catalysis

Satyanarayana¹,

Abraham²,

Kagan³

2008

Angew Chem Int Ed

500

273

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There is a need for the preparation of enantiomerically pure compounds for various applications. An efficient approach to achieve this goal is asymmetric catalysis. The chiral catalyst is usually prepared from a chiral auxiliary, which itself is derived from a natural product or by resolution of a racemic precursor. The use of non-enantiopure chiral auxiliaries in asymmetric catalysis seems unattractive to preparative chemists, since the anticipated enantiomeric excess (ee) of the reaction product should be proportional to the ee value of the chiral auxiliary (linearity). In fact, some deviation from linearity may arise. Such nonlinear effects can be rich in mechanistic information and can be synthetically useful (asymmetric amplification). This Review documents the advances made during the last decade in the use of nonlinear effects in the area of organometallic and organic catalysis.

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Section: Diels-alder Reactionsmentioning

confidence: 95%

Nonlinear Effects in Asymmetric Catalysis

Satyanarayana¹,

Abraham²,

Kagan³

2008

Angew Chem Int Ed

500

273

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“…We next examined chiral Brønsted acids, such as BINOL (1,1Ј-binaphthyl-2,2Ј-diol, 9) 47) and BNPPA (1,1Ј-binaphthalene-2,2Ј-diyl hydrogen phosphate, 10). [48][49][50][51][52][53] The L-Met-or L-Phe-mediated reaction in the presence of (R)-or (S)-BINOL (9) having a phenolic proton afforded (S)-8 as a major enantiomer with quite low ee (entries 3, 4, 10, 11). On the other hand, the reaction mediated by L-Met or L-Phe with (S)-BNPPA (10) as a chiral Brønsted acid gave almost the same result as that using TFA or TFSA (entries 5, 12).…”

Section: Resultsmentioning

confidence: 99%

Enantioselective Intramolecular Aldol Reaction Mediated by a Combination of L-Amino Acid and Bronsted Acid to Construct a Bicyclic Enedione Containing a 7-Membered Ring

Nakagawa

Inomata

Endo

2007

CHEMICAL & PHARMACEUTICAL BULLETIN

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Wieland-Miescher ketone (3), which was prepared by Lproline-mediated asymmetric intramolecular aldol reaction of the trione (1), has been a highly useful synthon in total syntheses of a variety of natural products. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] This asymmetric aldol reaction has become known as the HajosParrish-Eder-Sauer-Wiechert reaction, and has been widely recognized to involve an enamine-based mechanism. Uda and Hagiwara successfully extended the reaction to construct a Wieland-Miescher ketone derivative [(S)-7] bearing a methyl substituent at C-1. [38][39][40] However, there has been little development of this reaction for the purpose of constructing new ring systems encompassing a 7-membered or larger carbocycle. [41][42][43][44] Recently, we have reported the L-Met (Lmethionine)-mediated asymmetric intramolecular aldol reaction of the trione (5) to prepare a new bicyclic enedione [(R)-8] containing a 7-membered ring.45) Strikingly, the process was characterized by an inversion of enantioselectivity when compared with the similar reaction using the trione (4). 45,46) However, the ee value of the reaction to afford (R)-8 was only moderate (Chart 1). In connection with an ongoing synthetic project, we needed to improve this method. We report here new reaction conditions to prepare (R)-8 with higher ee than previously reported. Results and DiscussionThe starting trione (5) was prepared from diethyl adipate by the known method. 45) We then screened several commercially available acyclic L-amino acids, especially those bearing a branched or an unbranched alkyl chain, for the aldol reaction of 5. We had previously found that a Brønsted acid, such as (ϩ)-CSA (camphorsulfonic acid) or PPTS (pyridinium p-toluenesulfonate), played a very important role in determining the enantioselectivity, 45) because the reaction without a Brønsted acid afforded (S)-8 with a quite low ee. Therefore, all of the reactions were carried out under the same conditions in the presence of a stoichiometric amount of L-amino acid and 0.5 eq of PPTS in DMSO (dimethylsulfoxide) at 90°C (Chart 2). Ee (enantiomeric excesses) of the resulting enone [(R)-8] were determined by HPLC with a chiral stationary phase column (Chiralpak AS-H, Daicel Chemical Corporation, Ltd.). The absolute configuration of the enone (8) was assigned to be R by comparison of the optical rotation with the reported value.45) The results are compiled in Table 1.Although all of the reactions involving L-amino acids bearing alkyl side chains remained incomplete after 24 h, (R)-8 was obtained with almost the same ee values as in the case of The enantioselectivity of the intramolecular asymmetric aldol reaction of 1,3-cycloheptanedione bearing a C-2 methyl substituent, mediated by a series of combinations of L-amino acid and Brønsted acid, was examined in detail.

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“…[11k] 1 H and 13 C NMR spectra were recorded in deuteriochloroform (CDCl 3 ) or a mixture of deuteriochloroform with [D 4 ]MeOH (CD 3 OD), with tetramethylsilane (TMS) as an internal standard at ambient temperature with a Bruker Avance 400 spectrometer, operating at 400 MHz for 1 H, 100 MHz for 13 C, and 162 MHz for 31 P. All spectra were calibrated at δ = 0.00 ppm for 1 H spectra (TMS) and at 77.16 ppm for 13 C spectra (CDCl 3 ). Splitting pat-terns are designated as follows: s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet, br.…”

Section: Methodsmentioning

confidence: 99%

“…A very similar sequence of reactions involving protections and deprotections is utilized for the synthesis of 6,6Ј-disubstituted BNPHs 12, starting from commercially available 6,6Ј-dibromo-BINOL (8) as substrate (Scheme 2). [6,13] Scheme 2. Typical synthesis of chiral 6,6Ј-BNPH 12.…”

Section: Introductionmentioning

confidence: 99%

A Protecting‐Group‐Free Route to Chiral BINOL–Phosphoric Acids

Chiu

2011

Eur J Org Chem

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A two‐step, protecting group‐free route for the synthesis of 3,3′‐disubstituted and 6,6′‐disubstituted chiral BINOL–phosphoric acids has been realized starting from commercially available brominated BINOLs. This synthesis relies on the direct Suzuki coupling of brominated BINOL phosphoric acids. This synthetic strategy is more efficient compared to previous circuitous strategies involving protections and deprotections, and the process is higher yielding relative to the alternative two‐step synthesis involving Suzuki coupling of the BINOL.

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Chiral rare earth organophosphates as homogeneous Lewis acid catalysts for the highly enantioselective hetero-Diels–Alder reactions

Cited by 65 publications

References 68 publications

Nonlinear Effects in Asymmetric Catalysis

Nonlinear Effects in Asymmetric Catalysis

Enantioselective Intramolecular Aldol Reaction Mediated by a Combination of L-Amino Acid and Bronsted Acid to Construct a Bicyclic Enedione Containing a 7-Membered Ring

A Protecting‐Group‐Free Route to Chiral BINOL–Phosphoric Acids

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