Comparison of Solid-Phase and Solution-Phase Chiral Auxiliaries in the Alkylation/Iodolactonization Sequence to γ-Butyrolactones

Price, Michael D.; Kurth, Mark J.; Schore, Neil E.

doi:10.1021/jo0260692

Cited by 25 publications

(10 citation statements)

References 17 publications

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“…6 This phenomenon where the cross-linked polymer-supported version of a chiral auxiliary gives higher ee values than its solutionphase counterpart is not unique. 18 However at this stage, it is difficult to say how much of this is due to conformational constraints imposed by the cross-link environment, how much arises from other effects of the microenvironment such as modification in solvation in the polymer interior, or how much is due to the ratio between the racemic amine and the supported chiral reagent. However, we can probably rule out the latter as only 4% variation of the selectivity was previously observed when using 2 equivalents of amines instead of 3 (amine/reagent ratio of 2 vs 3 led to 86 vs 90% ee).…”

mentioning

confidence: 99%

Unprecedented, fully recyclable, solid-supported reagent for the kinetic resolution of racemic amines through enantioselective N-acetylation

et al. 2005

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The high-yielding synthesis and application of the first polymer supported reagent for the kinetic resolution (KR) of amines through enantioselective acetylation is described; this new supported chiral reagent allows the KR of primary amines with excellent selectivities at room temperature; moreover, this supported approach is highly efficient as the Merrifield-supported chiral scaffold can be quantitatively recovered and recycled.

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mentioning

confidence: 99%

Unprecedented, fully recyclable, solid-supported reagent for the kinetic resolution of racemic amines through enantioselective N-acetylation

et al. 2005

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“…Asymmetric alkylation reactions using polymer-supported chiral auxiliaries have not been widely investigated yet [17]. In this field, solid supported chiral auxiliaries such as Evans'2oxazolidinones [18] and pseudoephedrines [19][20][21][22][23][24][25][26][27][28][29] have been mainly explored. In this research we make modification of poly methylmethacrylate resins which facilitated the synthesis of 2-methyl butanoic acid in a good stereoselectivity.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of optically pure ant pheromones with high enantiomeric purity.

Ai¹,

Mh²,

Aa³

2018

Environ Risk Assess Remediat

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Chemical ecology studies with insects have founded that pheromonal communications often includes several components which can be linear, cyclic or heterocyclic compounds, in the case of chiral pheromones, insect often show the ability to characterize between and respond differently to stereoisomer. Among the most notable are those cases in which differential interspecific responses to enantiomer serve as a species isolating mechanism, the relationship between stereoisomers and pheromone activity are highly specific, meaningful assays and evaluation of the responses of insect to chiral pheromones must be carried out using substances of the highest possible chiral purity, we prepare ant pheromones using poly methyl methacrylate as chiral auxiliaries with high enantiomeric purity and the prepared compounds were characterized with spectroscopic data and the diastereomeric amides were separated using high performance liquid chromatography and give high enantiomeric excess, also we study the biological applications of our products and give agood results.

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“…13 (S)-(1-Isopropylpyrrolidin-2-yl)diphenylmethanol (38). (S)diphenyl(pyrrolidin-2-yl)methanol 77 (12.0 g, 47.3 mmol) was subjected to a reaction with acetone (13.8, 237 mmol), sodium cyanoborohydride (6.0 g, 95 mmol) in acetonitirle (100 mL) and acetic acid (0.1 mL) at ambient temperature for 18 h. The reaction was concentrated to an oily solid. The residue was dissolved in ethylacetate and water.…”

Section: Scheme 3 Mechanistic Proposal For the Water Effect On The Zi...mentioning

confidence: 99%

Zinc Catalyzed and Mediated Asymmetric Propargylation of Trifluoromethyl Ketones with a Propargyl Boronate

et al. 2013

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The development of zinc-mediated and -catalyzed asymmetric propargylations of trifluoromethyl ketones with a propargyl borolane and the N-isopropyl-l-proline ligand is presented. The methodology provided moderate to high stereoselectivity and was successfully applied on a multikilogram scale for the synthesis of the Glucocorticoid agonist BI 653048. A mechanism for the boron-zinc exchange with a propargyl borolane is proposed and supported by modeling at the density functional level of theory. A water acceleration effect on the zinc-catalyzed propargylation was discovered, which enabled a catalytic process to be achieved. Reaction progress analysis supports a predominately rate limiting exchange for the zinc-catalyzed propargylation. A catalytic amount of water is proposed to generate an intermediate that catalyzes the exchange, thereby facilitating the reaction with trifluoromethyl ketones.

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Comparison of Solid-Phase and Solution-Phase Chiral Auxiliaries in the Alkylation/Iodolactonization Sequence to γ-Butyrolactones

Cited by 25 publications

References 17 publications

Unprecedented, fully recyclable, solid-supported reagent for the kinetic resolution of racemic amines through enantioselective N-acetylation

Unprecedented, fully recyclable, solid-supported reagent for the kinetic resolution of racemic amines through enantioselective N-acetylation

Synthesis of optically pure ant pheromones with high enantiomeric purity.

Zinc Catalyzed and Mediated Asymmetric Propargylation of Trifluoromethyl Ketones with a Propargyl Boronate

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