The stereodivergent iridium‐catalyzed allylic alkylation and fluorination of acyclic ketones is described. α‐Pyridyl‐α‐fluoroketones with vicinal tertiary and quaternary stereocenters were obtained in moderate to excellent yields and stereoselectivities. Distinct from known stereodivergent synthesis, for which two different chiral catalysts are required in general, herein we report a sequence‐dependent stereodivergent synthesis. With only a single chiral Ir catalyst, all four possible stereoisomers of the products were prepared from the same starting materials by simply adjusting the sequence of asymmetric allylic alkylation and fluorination and varying the absolute configuration of the Ir catalyst.
Inspired by the unique character of enzymes, we developed novel chiral SPO (secondary-phosphine-oxide) ligand (SPO-Wudaphos) which can enter into both ion pair and H-bond noncovalent interactions. The novel chiral SPO-Wudaphos exhibited excellent results in the asymmetric hydrogenation of α-methylene-γ-keto carboxylic acids, affording the chiral γ-keto acids with up to over 99 % ee. A series of control experiments and DFT calculations were conducted to illustrate the critical roles of both the ion pair and H-bond noncovalent interactions.
The first interrupted asymmetric hydroaminomethylation reaction was developed. The challenging trans-1,2-disubstituted olefins were employed as substrates, and a series of valuable chiral pyrrolidinones and pyrrolidines were obtained in high yields with high regioselectivities and excellent enantioselectivities. Several synthetic transformations were conducted, demonstrating the high synthetic utility of our method. A creative route for the synthesis of vernakalant and Enablex was also developed.
Described herein is an asymmetric allylic aromatization (AAAr) strategy that employs readily accessible equivalents of benzylic nucleophiles in iridium-catalyzed allylic substitution reactions with the concomitant formation of aromatic rings by aromatization. The optimizedr eaction conditions involving ac atalyst derived from ac ommercially available iridium precursor and the Carreira ligand are compatible with equivalents of benzylic nucleophiles derived from 4-or 5-methyloxazoles,5 -methylthiazoles,4 -o r5methylfurans,2 -o r3 -methylbenzofurans,3 -methylbenzothiophene,3 -methylindole,1 -methylnaphthalene,a nd methylbenzene. This strategy provides straightforwarda ccesses to valuable heterocyclic aromatic compounds,b earing ah omobenzylic stereogenic center,inanenantiopure form and would be difficult to access otherwise.T he versatility of the reaction was showcased by the further elaboration of the products into useful building blocks and adrug analogue.
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