Cu(I)-Catalyzed Highly Diastereo- and Enantioselective Constructions of Boron/Carbon Vicinal Stereogenic Centers via Insertion Reaction

Abstract

The diastereoselective synthesis of boron and carbon vicinal stereogenic centers is a great challenge in current synthetic chemistry due to the paucity of efficient synthetic strategies. Herein, a Cu-catalyzed diastereo- and enantioselective B–H bond insertion reaction of ene-yne-ketones as furyl-carbene precursors has been developed using chiral bis­(oxazolines) (BOX) as the ligand, thus furnishing a series of densely functionalized products (42 examples) bearing both boron and carbon vicinal stereogenic centers in high enantioselectivity and high diastereoselectivity (up to 99% ee and > 20:1 dr) with good yields (up to 98%).

Accessing Functionalized Furans from Reacting Enynones and Enynals through Furyl Metal Carbenes

“…Recently, copper(I)-catalyzed diastereo-and enantioselective BÀ H insertion reaction has been disclosed by the Song group, using enynones 1 as furyl carbene precursors and 2-arylpyridineÀ boranes 18 (Scheme 9). [19] Employing the cationic Cu(MeCN) 4 PF 6 catalyst and chiral BOX ligand L1, a series of chiral furyl substituted borane compounds 19, featuring vicinal boron and carbon stereogenic centers, was synthesized in good yields with high enantio-, and stereoselectivities (up to 99 % ee and > 20 : 1 dr). Deuterium labeling experiments revealed a plausible mechanism.…”

Chirality Transfer of Stereogenic Boron Centers Enabled by a SN2-Type Mechanism

“…More recently, the focus moved to enantioenriched boron chelates with a single stereogenic center at the boron atom. The few reported syntheses of such boron N,N - or C,N -chelates rely on well-designed desymmetrization approaches. ,,, For example, a catalytic enantioselective C–H arylation furnishes the enantioenriched BODIPYs 2 which are useful, e.g., in chiral recognition or as chiroptical materials (Scheme a). , …”

“…The few reported syntheses of such boron N,N-or C,Nchelates rely on well-designed desymmetrization approaches. 1,2,15,16 For example, a catalytic enantioselective C−H arylation furnishes the enantioenriched BODIPYs 2 which are useful, e.g., in chiral recognition or as chiroptical materials (Scheme 1a). 1,15 Within this course, we developed a strategy for accessing enantioenriched boron C,N-chelates (S) B -4 via chirality transfer from aminoalcohol borinates (R) B -3 (Scheme 1b).…”

Unlocking Diverse π-Bond Enrichment Frameworks by the Synthesis and Conversion of Boronated Phenyldiethynylethylenes

“…Conjugated 1,3-diynes as simple and easily obtained building blocks are used extensively in natural products, industrial and pharmaceutical intermediates, as well as electronic and optical materials. Obviously, it is an attractive strategy for synthesizing functionally enriched organic π-conjugated 1,3-enyne frameworks, which are also of great importance in organic synthesis, biochemistry, and materials sciences, by the direct difunctionalization of 1,3-diynes (Scheme B). To further increase the structural diversity and late functional group ability of organic π-conjugated 1,3-enyne frameworks, the introduction of transformable functional groups should be considered.…”