Enantioselective Synthesis of Angularly Substituted 1-Azabicylic Rings: Coupled Dynamic Kinetic Epimerization and Chirality Transfer
作者:Zachary D. Aron、Tatsuya Ito、Tricia L. May、Larry E. Overman、Jocelyn Wang
DOI:10.1021/jo4018099
日期:2013.10.4
A new strategy for enantioselective synthesis of azacyclic molecules in which dynamickinetic equilibration of diastereomeric iminium ions precedes a stereochemistry-determining sigmatropic rearrangement is reported. The method is illustrated by the synthesis, in high enantiomeric purity (generally 95–99% ee), of a variety of 1-azabicyclic molecules containing angular allyl or 3-substituted 2-propenyl
Direct Catalytic Asymmetric Aminoallylation of Aldehydes: Synergism of Chiral and Nonchiral Brønsted Acids
作者:Hong Ren、William D. Wulff
DOI:10.1021/ja1110865
日期:2011.4.20
The development of a catalytic asymmetric method for the direct aminoallylation of aldehydes is described that gives high asymmetric inductions for a broad range of substrates including both aromatic and aliphatic aldehydes. This method allows for direct isolation of unprotected analytically pure homoallylic amines without chromatography. The unique catalyst system developed for this process involves
Highly Selective Addition of a Broad Spectrum of Trimethylsilane Pro-nucleophiles to <i>N</i>
-<i>tert</i>
-Butanesulfinyl Imines
作者:Manas Das、Donal F. O'Shea
DOI:10.1002/chem.201503354
日期:2015.12.14
Addition of organotrimethylsilane reagents to chiral N‐tert‐butanesulfinyl imines can be achieved in good yields and with excellent diastereoselectivities by employing TMSO−/Bu4N+ as a Lewis base activator in THF. A variety of aliphatic, aromatic, heteroaromatic and organometallic chiral imines were utilised as electrophiles for the synthesis of enantioenriched N‐tert‐butanesulfinyl amides. Remarkably
Highly Diastereoselective and Enantioselective Preparation of Homoallylic Amines: Application for the Synthesis of β-Amino Acids and γ-Lactams
作者:P. Veeraraghavan Ramachandran、Thomas E. Burghardt
DOI:10.1002/chem.200401295
日期:2005.7.18
furnished homoallylic amines in good yields and high ee. A 11B NMR spectroscopy study revealed that the reactions do not proceed, even at room temperature, unless a molar equivalent of water or methanol is added. The first reagent-controlled asymmetric crotylboration and alkoxyallylboration of aldimines furnishing beta-methyl or beta-alkoxy homoallylic amines in very high diastereoselectivity and enantioselectivity
<i>N</i>-Propargylamides via the Asymmetric Michael Addition of <i>B</i>-Alkynyl-10-TMS-9- borabicyclo[3.3.2]decanes to <i>N</i>-Acylimines
作者:Ana Z. Gonzalez、Eda Canales、John A. Soderquist
DOI:10.1021/ol0611595
日期:2006.7.1
The asymmetric synthesis of N-propargylamides through Michael addition of the alkynylborane 1 to N-acylimines is reported. The N-acetylimines provide the best substrates for the process exhibiting high selectivity (56-95% ee) with predictable stereochemistry. In several cases, 5 crystallizes in essentially pure form (97-99% ee) and a single-crystal X-ray structure was also obtained for 5g (R-1 = R-2 = Me, R-3 = o-Cl-C6C4). The process regenerates 4 for its direct conversion back to 1 and facilitates the efficient recovery of the pseudoephedrine.