Enantioselective Allylation of Indoles: A Surprising Diastereoselectivity.

Herein we show a novel approach toward the allylation of indoles. Thereby, we explore a class of bench-stable allylboronates and fine-tune their reactivity. The allylations of different substituted indoles proceed with negligible diastereo- and excellent enantioselectivities. This surprising selectivity (up to 99:1 er, up to ≈60:40 dr) is rationalized by DFT calculations.

Efficient Kinetic Resolution of Sulfur-Stereogenic Sulfoximines by Exploiting CpX RhIII -Catalyzed C-H Functionalization.

Chiral sulfoximines with stereogenic sulfur atoms are promising motifs in drug discovery. We report an efficient method to access chiral sulfoximines through a C-H functionalization based kinetic resolution. A rhodium(III) complex equipped with a chiral Cpx ligand selectively participates in conjunction with phthaloyl phenylalanine in the C-H activation of just one of the two sulfoximine enantiomers. The intermediate reacts with various diazo compounds, providing access to chiral 1,2-benzothiazines with synthetically valuable substitution patterns. Both sulfoximines and 1,2-benzothiazines were obtained in high yields and excellent enantioselectivity, with s-values of up to 200. The utility of the method is illustrated by the synthesis of the key intermediates of two pharmacologically relevant kinase inhibitors.

Highly Enantioselective Allylation of Ketones: An Efficient Approach to All Stereoisomers of Tertiary Homoallylic Alcohols.

An optimized protecting group for allylboronates allowed the use of ketones in order to synthesize all isomers of quaternary homoallylic alcohols with high enantioselectivities. All symmetric isomers of the allylboronate were prepared in high yields and diastereoselectivities using Sn 2' reactions. The improved reactivity of the novel protecting group was verified by following the reaction kinetics with 1 H NMR spectroscopy. Mechanistic studies using DFT calculations were conducted to investigate the new findings. Thus, the stereochemical outcome and enhanced reactivity can be rationalized.

Enantioselective Catalysts for the Synthesis of α-Substituted Allylboronates--An Accelerated Approach towards Isomerically Pure Homoallylic Alcohols.

The use of a convenient protecting group for boronates allows a selective, catalyzed S(N)2' reaction to generate allylboronates which are applied for the synthesis of enantiomerically pure homoallylic alcohols. Depending on the configuration of both catalyst and the protecting group any of the four possible stereoisomers can be formed. The rationale behind the selective addition is supported by density functional theory calculations.