Spirocycles are attractive synthetic targets for many synthetic chemists owing to their potent and promising biological activities. We previously reported a method for the highly enantioselective allylation of various isatins with β‐amido‐functionalized allylstannanes under the influence of indium‐based chiral catalysts and applied this method to the synthesis of 2‐oxindole derivatives spiro‐fused to an α‐methylene‐γ‐butyrolactone framework. In this communication, we report the successful development of a new catalytic system that enables enantioselective tin‐free “amide allylation” with the aid of a newly prepared (β‐amidoallyl)boronate for nucleophilic addition to isatins. This system consisting of a catalytic amount of diethylzinc as a competitive candidate in the presence of chiral 1,3‐amino alcohols incorporating an acidic phenol functionality offers new opportunities for environmentally benign access to medicinally relevant spirocyclic 2‐oxindoles.
Enantioselective allylation of aldehydes and ketones is a widely used approach for preparing chiral homoallylic alcohols, however, most of the reactions are still mainly performed in organic solvents. Considering their environmental impact, expansion of synthetic technology in water has the highest priority in the organic chemistry field. Here, we report enantioselective reaction of water‐stable amido‐functionalized allylboronates with acetophenone derivatives in water. The reaction was catalyzed with zinc hydroxide and a didecylamino‐functionalized chiral aminophenol reagent, affording a variety of homoallylic alcohols in up to 99% yield. There is a definite proportional correlation between the enantioselectivity and the size of an ortho‐substituent on the substrate, and the enantiomeric excess of the product reached up to 98%.
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