First Asymmetric Total Synthesis of (+)-Sparteine

Smith, Brenton T.; Wendt, John A.; Aubé, Jeffrey

doi:10.1021/ol026230v

Cited by 127 publications

(83 citation statements)

References 14 publications

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“…[20Ϫ23] However, the preparation of enantiopure α-aminoalkyltriorganotins as potential precursors of enantiopure α-amino anions upon transmetallation with nbutyllithium appears to offer great potential [24,25] and initiated our investigations into the synthesis of N-protected 2-triorganostannyl-1,3-oxazolidines. The advantage of this approach in comparison with enantioselective deprotonation by n-butyllithium or sec-butyllithium in the presence of (Ϫ)-sparteine [26Ϫ30] , (ϩ)-sparteine [31] or a (ϩ)-sparteine surrogate derived from cytisine [32] should be the obtaining of chiral α-aminoorganolithium reagent uncomplexed with a diamine ligand. Accordingly, an efficient route to provide 2-triorganostannyl-1,3-oxazolidines selectively would seem to be of great interest in order subsequently to provide chiral α-aminoorganostannanes through ring opening of the oxazolidine component.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Chiral 2‐Stannyloxazolidines and First Considerations on the Transacetalisation Reaction Mechanism

et al. 2004

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N‐Protected 2‐tributylstannyl‐1,3‐oxazolidines derived from N‐monoprotected chiral β‐amino alcohols were obtained through transacetalisation of (diethoxymethyl)tributylstannane under acidic conditions. In the case of 4‐substituted 2‐tributylstannyl‐1,3‐oxazolidines, the kinetic product of the reaction was shown to be the trans isomer whatever the nature of the protective group, while the thermodynamic product was the cis isomer in the N‐Ts series and the trans isomer in N‐CO2R compounds. Aspects of the transacetalisation reaction are discussed along with those concerning the isomerisation of the products, allowing an interpretation of the obtained results. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Section: Introductionmentioning

confidence: 99%

Preparation of Chiral 2‐Stannyloxazolidines and First Considerations on the Transacetalisation Reaction Mechanism

et al. 2004

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“…[21] Amide reduction completed the synthesis of (À)-sparteine,which was isolated as the bisulfate salt, [24] after recrystallization, in 67 %yield. [25] Theoptical rotation (of the free base,[ a] D = (À)20.4 (c = 1.0, EtOH);l it., [17] [a] D = (À)20.7 (c = 1.8, EtOH)) confirmed that (À)-sparteine had been synthesised. Overall, this diastereocontrolled synthesis of (À)-sparteine was completed in 10 steps (longest linear sequence [23] )i n3 1% yield.…”

mentioning

confidence: 72%

“…[13] Over the years,our group [10,14] and others [15] have explored synthetic approaches to enantiopure (+ +)-and (À)-sparteine surrogate.However,all approaches are either inconveniently long,lack diastereo-and/or regioselectivity,only allow access to one enantiomer,a nd/or proceed with overall low yields. These limitations have thus far precluded the synthesis of enantiopure (+ +)-and (À)-sparteine surrogate on agram-scale and addressing this is the primary topic of this paper.I n addition, in designing our new approach to the sparteine surrogate,w er ecognized that it could also be adapted to deliver an ew resolution/reconnection strategy for the gramscale synthesis of (À)-sparteine.Despite numerous syntheses of racemic sparteine over 65 years, [16] there are only two enantioselective syntheses (by AubØ [17] and our group [18] ), which delivered around 50 mg quantities of (+ +)-or (À)-sparteine over long or low-yielding approaches.…”

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confidence: 99%

Gram‐Scale Synthesis of the (−)‐Sparteine Surrogate and (−)‐Sparteine

et al. 2017

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An 8-step,gram-scale synthesis of the (À)-sparteine surrogate (22 %y ield, with just 3c hromatographic purifications) and a1 0-step,g ram-scale synthesis of (À)-sparteine (31 %y ield) are reported. Both syntheses proceed with complete diastereocontrol and allow access to either antipode. Since the syntheses do not rely on natural product extraction, our work addresses long-term supply issues relating to these widely used chiral ligands.The natural product sparteine and its structurally related cousin, the sparteine surrogate (Scheme 1), which was developed in our laboratory, [1] are widely used chiral ligands in asymmetric synthesis.Inparticular, these diamines are the "go-to" chiral ligands for organolithium bases such as sBuLi [2] foruse in reactions pioneered in the 1990s by Hoppe [3] and Beak.[4] Themore recent work from the Aggarwal group on programmable assembly-line synthesis [5] using chiral boron reagents (generated from s-BuLi/chiral diamine-mediated asymmetric lithiations) has significantly expanded the synthetic potential offered by sparteine and the sparteine surrogate.

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“…However, the original synthesis was challenging because the precursor (R,R)-1-BH 3 had to be prepared with (+)-sparteine. 137 The problem was solved by the development of another reaction route. Scheme 2 shows the new synthetic route to obtain both (S,S)-3-BH 3 and (R,R)-3-BH 3 from 5-BH 3 with the only (− )-sparteine.…”

Section: P-stereogenic Cyclic Phosphines For Chiral Element-blocksmentioning

confidence: 99%

Recent progress in the development of advanced element-block materials

Gon

Tanaka

Chujo

2017

Polym J

127

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An element-block is defined as a minimum functional unit composed of heteroatoms. The concept of 'element-block material' for designing advanced materials was proposed in 2015. In this review, the recent progress in material designs based on this concept is described. From our research, several element-blocks as representative examples are selected, and their roles in each material are explained. Initially, research on the development of 'designable hybrids' by employing polyhedral oligomeric silsesquioxane (POSS) is illustrated. Multiple functions of hybrids composed of modified POSS and the significant roles of POSS in bio-related polymeric materials for solving critical problems in conventional 19 F MR probes and for realizing new sensing technologies are demonstrated. Next, solid-state luminescent materials containing o-carborane and group 13 element-blocks are discussed. The materials' highly efficient emission in the solid state and their origins are explained. Furthermore, stimuliresponsive luminescent chromism is summarized. The sensing mechanisms and the application of these materials as sensors are presented in this study. In the last part, we mention optically active element-blocks containing chiral P-stereogenic phosphorus. In this review, the characteristics originating from each element-block are explained.

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First Asymmetric Total Synthesis of (+)-Sparteine

Cited by 127 publications

References 14 publications

Preparation of Chiral 2‐Stannyloxazolidines and First Considerations on the Transacetalisation Reaction Mechanism

Preparation of Chiral 2‐Stannyloxazolidines and First Considerations on the Transacetalisation Reaction Mechanism

Gram‐Scale Synthesis of the (−)‐Sparteine Surrogate and (−)‐Sparteine

Recent progress in the development of advanced element-block materials

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