In stereochemistry, a chiral auxiliary is a stereogenic group or unit that is temporarily incorporated into an organic compound in order to control the stereochemical outcome of the synthesis. [1] [2] The chirality present in the auxiliary can bias the stereoselectivity of one or more subsequent reactions. The auxiliary can then be typically ...

亲核试剂（nucleophile，意思为原子核的喜好物）， 又叫亲核基，指具有亲核性的化学试剂，可用：Nu表示。 一些带有未共享电子对的分子或负离子，与正电性碳反应时称为亲核试剂。

A chiral auxiliary is a chiral molecule derived from Nature that is attached to the reaction substrate to provide facial selectivity and orientation control in a reaction, and can be removed afterwards to regenerate the original functional group.

Chiral auxiliary aided a-alkylation of a carbonyl group can provide high enantioselectivity for most substrates, and the hydrazone method can provide routes to a large variety of a-substituted carbonyl compounds.

1993年11月1日 · Studies on asymmetric conversion of arenes to functionalized cyclohexenones via chiral auxiliary-promoted nucleophilic additions to arene-chromium complexes. Tetrahedron Letters 1996 , 37 (18) , 3087-3088.

1997年3月17日 · A combination of sterically demanding, very reactive nucleophile gives best results that can be understood based on an intuitive steric approach control model, while nucleophiles of lower reactivity give poorer or even reversed selectivity that appears to be consistent with a late transition state model.

2023年1月23日 · Nucleophilicity depends on many factors, including charge, basicity, solvent, polarizability, and the nature of the substituents. Nucleophiles can be neutral or negatively charged. In either case, it is important that the nucleophile be a good Lewis base, meaning it has electrons it wants to share.

OxymaPure® used with DIC produces peptides with increased yield and decreased epimerization when used as an alternative to HOBt. 1 This safe, non-explosive auxiliary nucleophile works with carbodiimide coupling strategies to provide the best results for a peptide synthesis.

2022年7月20日 · A nucleophile is an atom or functional group with a pair of electrons (usually a non-bonding, or lone pair) that can be shared. The same, however, can be said about a base: in fact, bases can act as nucleophiles, and nucleophiles can act as bases. What, then, is the difference between a base and a nucleophile?

2024年1月26日 · Identify nucleophiles and electrophiles, their similarities, and differences from acids and bases. Understand SN2, E2, SN1, or E1 reaction mechanisms, factors that affect them, and conditions that dictate which one will take place. Learn some examples of SN2, E2, SN1, and E1 reactions of alcohols, ethers, amines, and thiols.