Chiral Bifunctional Sulfide‐Catalyzed Highly Enantioselective Bromolactonizations of 4‐Pentenoic Acids

Abstract

Despite extensive studies into the design of effective chiral catalysts for asymmetric halolactonizations, the development of highly enantioselective catalytic bromolactonization of 4-aryl-4-pentenoic acids, which is one of the benchmark reactions, has not been completely satisfactory. Herein, we report the use of BINOL-derived chiral bifunctional sulfide catalysts to achieve highly enantioselective bromolactonizations of 4-aryl-4-pentenoic acids. The importance of the bifunctional design of chiral sulfide catalysts was clearly demonstrated in the present study. Furthermore, the present catalytic asymmetric reaction system could be applied to highly stereoselective desymmetrizing bromolactonizations.

Chiral sulfide and selenide catalysts for asymmetric halocyclizations and related reactions

“…The powerful potential of the hydroxy-type chiral bifunctional sulfide catalysts ( S )- 8 was further demonstrated by the highly enantioselective bromolactonization of 4-aryl-4-pentenoic acids, 29 which is one of the benchmark asymmetric halocyclization reactions (Scheme 21). 30 The highest levels of enantioselectivity yet reported for the asymmetric synthesis of γ-quaternary γ-butyrolactones via bromolactonizations have been observed by utilizing bifunctional sulfide ( S )- 8d .…”

“…Catalytic asymmetric iodolactonizations of 4-aryl-4-pentenoic acids were also examined using the hydroxy-type chiral bifunctional sulfide catalysts ( S )- 8 , which were quite effective for bromolactonizations (Scheme 22). 29 Surprisingly, however, the asymmetric iodolactonization of 4-phenyl-4-pentenoic acid using chiral sulfide catalysts ( S )- 8d or 8e provided a corresponding γ-butyrolactone product in a racemic form. On the other hand, related hydroxy-type chiral selenide catalysts ( S )- 10 showed good catalytic performance to give an iodolactonization product in moderate to good levels of enantioselectivity.…”

“…Catalytic asymmetric iodolactonizations of 4-aryl-4-pentenoic acids were also examined using the hydroxy-type chiral bifunctional sulfide catalysts (S)-8, which were quite effective for bromolactonizations (Scheme 22). 29 Surprisingly, however, Scheme 18 Amide-type chiral bifunctional sulfide-catalyzed desymmetrizing bromolactonizations of α,α-dipropargyl carboxylic acids.…”

Chiral Bifunctional Selenide Catalysts for Asymmetric Iodolactonizations

“…In this context, we have recently developed 1,1′-bi-2-naphthol (BINOL)-derived chiral bifunctional chalcogenide catalysts for enantioselective bromolactonizations. [22][23][24][25][26][27][28][29][30] When our chiral bifunctional sulfide catalyst (S)-3 was submitted to the bromolactonization of alkenyl carboxylic acid 1 as a benchmark reaction, the corresponding γ-butyrolactone product 2 (X = Br) was obtained in a highly enantioselective manner via the formation of a highly organized transition-state structure. 28) The related chiral bifunctional selenide catalyst (S)-4 also served as an effective catalyst for the bromolactonization.…”

“…[22][23][24][25][26][27][28][29][30] When our chiral bifunctional sulfide catalyst (S)-3 was submitted to the bromolactonization of alkenyl carboxylic acid 1 as a benchmark reaction, the corresponding γ-butyrolactone product 2 (X = Br) was obtained in a highly enantioselective manner via the formation of a highly organized transition-state structure. 28) The related chiral bifunctional selenide catalyst (S)-4 also served as an effective catalyst for the bromolactonization. 26) To expand the utility of our chiral bifunctional chalcogenide catalysts for asymmetric halolactonizations, we drew out an iodolactonization of 1 under the influence of our chiral bifunctional chalcogenides in this work.…”