Use of Pseudoephedrine as a Practical Chiral Auxiliary for Asymmetric Synthesis

Myers, Andrew G.; Yang, Bin; Chen, Hou; Gleason, James L.

doi:10.1021/ja00099a076

Cited by 245 publications

(108 citation statements)

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“…When R becomes too bulky the amine approach is very dependent on both the R and amine protection. In the last case, addition of LiC1 favoured the formation of the E zwitterion, as already reported for enolates (Seebach, 1988;Galiano-Roth et al, 1991;Humphrey et al, 1994;Myers et al, 1994;R~ick, 1995;Majewski et al, 1995).…”

Section: Stereoselective Synthesis Of Amino Acid Derivatives Through supporting

confidence: 78%

Some of the amino acid chemistry going on in the Laboratory of Amino Acids, Peptides and Proteins

et al. 1999

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Some of the chemistry of amino acids going on in our laboratory (Laboratoire des Amino acides Peptides et Protéines) is described as well as some mass spectrometry methodology for their characterization particularly on solid supports. Several aspects are presented including: (i) the stereoselective synthesis of natural and unnatural amino acids using 2-hydroxypinan-3-one as chiral auxiliary; (ii) the stereoselective synthesis of natural and unnatural amino acids by deracemization of alpha-amino acids via their ketene derivatives; (iii) the synthesis of alpha-aryl-alpha-amino acids via reaction of organometallics with a glycine cation; (iv) the diastereoselective synthesis of glycosyl-alpha-amino acids; (v) the synthesis of beta-amino acids using alpha-aminopyrrolidinopiperazinediones as chiral templates; (vi) the reactivity of urethane-N-protected N-carboxyanhydrides. To characterize natural and non natural amino acids through their immonium ions by mass spectrometry, some methodology is also described.

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Section: Stereoselective Synthesis Of Amino Acid Derivatives Through supporting

confidence: 78%

Some of the amino acid chemistry going on in the Laboratory of Amino Acids, Peptides and Proteins

et al. 1999

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“…Myers has developed a robust iterative alkylation protocol using stoichiometric ephedrine-based auxiliaries that provides access to all possible stereochemical variants, 75–76 and Theodorakis has applied this methodology in the total synthesis of (−)-borrelidin (figure 2e). 77–78 …”

Section: Many Customized Iterative Synthesis Methods Have Already Beementioning

confidence: 99%

Towards the generalized iterative synthesis of small molecules

2018

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Small molecules have extensive untapped potential to benefit society, but access to this potential is too often restricted by limitations inherent to the customized approach currently used to synthesize this class of chemical matter. In contrast, the “building block approach”, i.e., generalized iterative assembly of interchangeable parts, has now proven to be a highly efficient and flexible way to construct things ranging all the way from skyscrapers to macromolecules to artificial intelligence algorithms. The structural redundancy found in many small molecules suggests that they possess a similar capacity for generalized building block-based construction. It is also encouraging that many customized iterative synthesis methods have been developed that improve access to specific classes of small molecules. There has also been substantial recent progress toward the iterative assembly of many different types of small molecules, including complex natural products, pharmaceuticals, biological probes, and materials, using common building blocks and coupling chemistry. Collectively, these advances suggest that a generalized building block approach for small molecule synthesis may be within reach.

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“…Access to the required acid segment was based on an iterative use of the excellent asymmetric alkylation methodology developed by Myers and co-workers (Scheme 6). [34] Specifically, reaction of the pseudo-ephedrine derived propion-A C H T U N G T R E N N U N G amide 22 with iodide 24 mediated by LDA in the presence of LiCl afforded 25 in high yield and diastereoselectivity (de > 99 %) on a multigram scale. This product was converted into iodide 27, which then served as electrophilic component in the next alkylation step with ent-22.…”

Section: Preparation Of the Building Blocks-the Western Fragmentmentioning

confidence: 99%

“…1 (25): nBuLi (1.6 m in hexane, 13.1 mL, 21.0 mmol) was slowly added to a suspension of LiCl (2.54 g, 59.9 mmol) and (iPr) 2 NH (3.16 mL, 22.5 mmol) in THF (12 mL) at À78 8C before the resulting mixture was allowed to reach ambient temperature. After stirring for 10 min, the mixture was cooled to À78 8C before a pre-cooled (0 8C) solution of amide 22 (2.21 g, 9.99 mmol) [34] in THF (33 mL) was introduced. After stirring for 1 h at that temperature and for an additional 20 min at 0 8C, a solution of iodide 24 (4.92 g, 15.0 mmol) in THF (63 mL) was added dropwise at 0 8C over a period of 1 h and stirring continued until TLC showed complete conversion.…”

Section: Western Segmentmentioning

confidence: 99%

Total Synthesis of Myxovirescin A₁

Fürstner¹,

Bonnekessel²,

Blank³

et al. 2007

Chemistry A European J

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A convergent total synthesis of the antibiotic macrolide myxovirescin A1 (1) is described that is largely based on reagent- and catalyst-controlled transformations. This includes a highly regioselective Negishi reaction of dibromo-alkene 48 with an alkynylzinc reagent, and a palladium catalyzed alkyl-Suzuki coupling of the resulting enyne derivative 12 with the 9-BBN-adduct derived from alkene 61. The latter was obtained via an asymmetric hydrogenation of the chlorinated beta-ketoester 49 and an anti-selective oxyallylation of the functionalized aldehyde 53 as the key steps. The preparation of the bis-borylated allyl-donor 57 used in the oxyallylation step, however, required careful optimization and led to important insights into the nature of the classical hydroborating agent "di(isopinocampheyl)borane (Ipc2BH)". It was unambiguously shown by X-ray crystallography that in the solid state this compound is dimeric, but it is prone to undergo an essentially quantitative mono-deborylation when dissolved in CH2Cl2 or benzene; its composition in ethereal solvents is even more complex as evident from 11B NMR data. Product 71 derived from 12 and 61 was elaborated into the enyne-yne derivative 75, which served as the substrate for an exquisitely selective ring closing alkyne metathesis reaction (RCAM) catalyzed by the molybdenum tris-amido complex 20 activated in situ with CH2Cl2. The resulting cyclic enyne 76 was subjected to a ruthenium catalyzed trans-hydrosilylation/proto-desilylation tandem. Although [Cp*Ru(MeCN)3]PF6 had previously been recommended as catalyst of choice for trans-hydrosilylation reactions of internal alkynes, this complex failed to afford the desired product, whereas its sterically less hindered congener [CpRu(MeCN)3]PF6 permitted the reaction to be performed in appreciable yield, but at the expense of a lower stereoselectivity. AgF-mediated proto-desilylation of the isomeric silanes 79 and 80 followed by cleavage of the remaining acetal protecting groups afforded myxovirescin A1 and its hitherto unknown 14Z-isomer 81, respectively.

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Use of Pseudoephedrine as a Practical Chiral Auxiliary for Asymmetric Synthesis

Cited by 245 publications

References 0 publications

Some of the amino acid chemistry going on in the Laboratory of Amino Acids, Peptides and Proteins

Some of the amino acid chemistry going on in the Laboratory of Amino Acids, Peptides and Proteins

Towards the generalized iterative synthesis of small molecules

Total Synthesis of Myxovirescin A₁

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Use of Pseudoephedrine as a Practical Chiral Auxiliary for Asymmetric Synthesis

Cited by 245 publications

References 0 publications

Some of the amino acid chemistry going on in the Laboratory of Amino Acids, Peptides and Proteins

Some of the amino acid chemistry going on in the Laboratory of Amino Acids, Peptides and Proteins

Towards the generalized iterative synthesis of small molecules

Total Synthesis of Myxovirescin A1

Contact Info

Product

Resources

About

Total Synthesis of Myxovirescin A₁