Highly enantioselective cyclization using cationic Rh(I) with chiral ligand

Wu, Xueyuan; Funakoshi, Kazuhisa; Saito, Kiyoshi

doi:10.1016/s0040-4039(00)60966-8

Cited by 60 publications

(16 citation statements)

References 6 publications

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“…66 The γ,δ-unsaturated aldehyde 105 undergoes cycloisomerization to afford the cyclopentanone 106 in greater than 99% enantiomeric excess (Equation 43). 67 Although cyclopentanones form most readily, the synthesis of cyclohexanones is also known. In the cycloisomerization of 107 the tolerance of Lewis basic sites is noteworthy (Equation 44).…”

Section: Intramolecular Hydroacylationmentioning

confidence: 99%

Transition Metal Catalyzed Cycloisomerizations

Trost¹,

Krische²

1998

Synlett

446

153

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IntroductionThe increasing need for environmentally responsible means of preparing the diverse range of chemical products demanded by society drives the quest for synthetic efficiency. Thus, in order to minimize the usage of raw materials and waste production, a chemical reaction should proceed with high levels of atom economy 1 and selectivity (chemo-, regio-, diastereo-, and enantioselectivity). Toward this ideal, the use of homogeneous transition metal catalysts in conjunction with chiral ligand fields has garnered much success.This review will focus upon the subset of transition metal catalyzed carbon-carbon bond forming reactions that occur intramolecularly and proceed with quantitative atom economy, i.e. cycloisomerization reactions. Related metal catalyzed cycloadditions, such as the metal catalyzed Diels-Alder and carbonylations like the Pauson-Khand reactions, are not discussed. Since natural product synthesis is often the arena in which the scope and limitation of methodologies are assessed, emphasis will be placed on the transformation of substrates en route to complex organic molecules. Survey of Reaction Types A. Ene-Type CyclizationsThe ene reaction 2a-d as defined by Alder 3 is an indirect substitutive addition reaction of an olefin containing an allylic hydrogen (the "ene" partner) with a molecule containing a π-bond (the "enophile").Abstract: Transformations that occur with complete atom economy minimize utilization of raw material and produce no waste and thus represent an upper limit of synthetic efficiency. Transition metal catalyzed cycloisomerizations represent a major class of atom economical reactions. Examples of the myriad of reaction types involving transition metal catalyses that comprise this class of chemical transformations are presented herein.

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Section: Intramolecular Hydroacylationmentioning

confidence: 99%

Transition Metal Catalyzed Cycloisomerizations

Trost¹,

Krische²

1998

Synlett

446

153

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“…The cyclization of 1 a using other ligands instead of dppe, such as 1,3‐bis(diphenylphosphanyl)propane (dppp), 1,2‐bis(diphenylphosphanyl)butane (dppb), and PPh 3 , gave no or only trace amounts of cyclized products 2 a, 2′a , and 3 a along with recovery of the starting material 1 a in 54–73 %. Interestingly, the use of ( R )‐BINAP ([1,1′‐binaphthalene]‐2,2′‐diylbis(diphenylphosphane)) in this cyclization gave only 2 a in 75 % yield, although the enantiomeric excess of 2 a was very low (3 % ee ) 7…”

Section: Methodsmentioning

confidence: 99%

A New Method for the Synthesis of Cycloheptenones by RhI-Catalyzed Intramolecular Hydroacylation of 4,6-Dienals

2002

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The development of methodology for the synthesis of cyclic compounds is important in modern synthetic organic chemistry, not least because there are many biologically active compounds with complicated cyclic structures. The construction of a medium-sized ring is relatively difficult due to unfavorable entropy and nonbonding interactions occurring at the transition state during the cyclization. Transition metal catalyzed cyclization is one of the most promising strategies for the construction of such medium-sized ring compounds. [1] Rh I -mediated cyclization of 4-alkenals to give cyclopentanone derivatives was first reported by Sakai et al. in 1972, [2] and this hydroacylation has subsequently been developed into a catalytic process [3] and asymmetric reaction. [4] On the basis of results of mechanistic studies, [5] it is thought that the reaction proceeds as follows (Scheme 1): a CÀH bond of the aldehyde moiety of 1 is oxidatively added to a Rh I complex followed by insertion of a C C bond of an olefin to give the rhodacycle intermediate I. Reductive elimination from I occurs to produce cyclopentanone 2 along with regeneration of the Rh I complex. We speculated that if a and recycled for 1.5 h. This process was repeated for the addition of the next three amino acids, Fmoc-glycine-Pfp, 5, and Fmoc-glycine-Pfp. After completion of the fifth coupling the resin was washed with CH 2 Cl 2 for 15 minutes, and the beads were removed from the synthesizer and dried overnight. 4-ä Molecular sieves (5 beads) and CH 2 Cl 2 (1 mL) were added to the resin beads, and the suspension was agitated for 1 h. TfOTMS solution (160 mL of a 16 % v/v solution in CH 2 Cl 2 ) was added to a solution of NIS (400 mg, 1.78 mmol in THF (4 mL) and CH 2 Cl 2 (1 mL). A 1.25-mL aliquot of the resulting mixture was added to the resin beads, and the suspension was agitated for 18 h. The solution was then removed by filtration, and the resin was washed with CH 2 Cl 2 (3 Â 2.5 mL). The resin was treated with 20 % piperidine in CH 2 Cl 2 (2 mL), and the mixture was agitated for 15 min. The solvent was drained and the resin was washed with CH 2 Cl 2 (3 Â 2.5 mL). A solution of NaOH (10 mg, 0.25 mmol) in THF (0.5 mL) and methanol (2 mL) was transferred to the resin beads. The mixture was then agitated for 1 h, after which the solution was filtered from the resin and the filtrate concentrated to dryness under reduced pressure. The crude products were dissolved in CH 2 Cl 2 (5 mL), washed with water (2 Â 5 mL), and dried (MgSO 4 ), and the major a isomer was purified by preparative HPLC on an Alltech Econosil Silica normal-phase preparative column (10 mm, 250 Â 22 mm) with a flow rate of 10 mL min À1 and gradient elution (0 min: hexane 95 %, 2-propanol 5 %; 20 min: hexane 65 %, 2-propanol 35 %; then isocratic for 5 min) to give 9a (14 mg).

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“…Upon further consideration, a possible one-step cyclization of aldehyde (−)- 20 to ketone (−)- 22 (Protocol 3), which comprise constitutional isomers, was explored employing an intramolecular hydroacylation reaction 24 utilizing Rh[NBD] 2 BF 4 /(±)-BINAP. 25 Pleasingly, (−)- 22 was generated in 77% yield. Unfortunately, use of less than a stoichiometric amount of the [Rh] reagent and/or a lower reaction temperature led to a significant decrease in reaction rate, likely due to the steric hindrance of the neopentyl aldehyde (−)- 20 .…”

mentioning

confidence: 99%

Total Synthesis of (−)-Nodulisporic Acids D, C, and B: Evolution of a Unified Synthetic Strategy

Zou

Yang

et al. 2018

J. Am. Chem. Soc.

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A unified synthetic strategy leading to the total synthesis of (-)-nodulisporic acids D, C, and B is described. Key synthetic transformations include a nickel-chromium-mediated cyclization, an aromatic ring functionalization employing a novel copper-promoted alkylation, a palladium-catalyzed cross-coupling cascade/indole ring construction, and a palladium-mediated regio- and diastereoselective allylic substitution/cyclization reaction, the latter to construct ring D.

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Highly enantioselective cyclization using cationic Rh(I) with chiral ligand

Cited by 60 publications

References 6 publications

Transition Metal Catalyzed Cycloisomerizations

Transition Metal Catalyzed Cycloisomerizations

A New Method for the Synthesis of Cycloheptenones by RhI-Catalyzed Intramolecular Hydroacylation of 4,6-Dienals

Total Synthesis of (−)-Nodulisporic Acids D, C, and B: Evolution of a Unified Synthetic Strategy

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