Enantioselective Intermolecular C-H Silylation of Heteroarenes for the Synthesis of Acyclic Si-Stereogenic Silanes.

Intermolecular C-H silylation for the synthesis of acyclic silanes bearing a silicon-stereogenic center in one enantiomeric form remains unknown to date. Herein, we report the first enantioselective intermolecular C-H silylation of heteroarenes for the synthesis of acyclic silicon-stereogenic heteroarylsilanes. This process undergoes a rhodium-catalyzed direct intermolecular dehydrogenative Si-H/C-H cross-coupling, giving access to a variety of acyclic heteroarylated silicon-stereogenic monohydrosilanes, including bis-Si-stereogenic silanes, in decent yields with excellent chemo-, regio-, and stereo-control, which significantly enlarge the chemical space of the optically active silicon-stereogenic monohydrosilanes.

Catalytic Enantioselective Dehydrogenative Si-O Coupling to Access Chiroptical Silicon-Stereogenic Siloxanes and Alkoxysilanes.

A rhodium-catalyzed enantioselective construction of triorgano-substituted silicon-stereogenic siloxanes and alkoxysilanes is developed. This process undergoes a direct intermolecular dehydrogenative Si-O coupling between dihydrosilanes with silanols or alocohols, giving access to a variety of highly functionalized chiral siloxanes and alkoxysilanes in decent yields with excellent stereocontrol, that significantly expand the chemical space of the silicon-centered chiral molecules. Further utility of this process was illustrated by the construction of CPL-active (circularly polarized luminescence) silicon-stereogenic alkoxysilane small organic molecules. Optically pure bis-alkoxysilane containing two silicon-stereogenic centers and three pyrene groups displayed a remarkable glum value with a high fluorescence quantum efficiency (glum = 0.011, ΦF = 0.55), which could have great potential application prospects in chiral organic optoelectronic materials.

Enantioselective construction of six- and seven-membered triorgano-substituted silicon-stereogenic heterocycles.

The exploitation of chirality at silicon in asymmetric catalysis is one of the most intriguing and challenging tasks in synthetic chemistry. In particular, construction of enantioenriched mediem-sized silicon-stereogenic heterocycles is highly attractive, given the increasing demand for the synthesis of novel functional-materials-oriented silicon-bridged compounds. Here, we report a rhodium-catalyzed enantioselective construction of six- and seven-membered triorgano-substituted silicon-stereogenic heterocycles. This process undergoes a direct dehydrogenative C-H silylation, giving access to a wide range of triorgano-substituted silicon-stereogenic heterocycles in good to excellent yields and enantioselectivities, that significantly enlarge the chemical space of the silicon-centered chiral molecules. Further elaboration of the chiral monohydrosilane product delivers various corresponding tetraorgano-substituted silicon-stereogenic heterocycles without the loss of enantiopurity. These silicon-bridged heterocycles exhibit bright blue fluorescence, which would have potential application prospects in organic optoelectronic materials.

Streamlined Construction of Silicon-Stereogenic Silanes by Tandem Enantioselective C-H Silylation/Alkene Hydrosilylation.

A rhodium-catalyzed tandem enantioselective C-H silylation/alkene hydrosilylation of dihydrosilanes, which enables the streamlined construction of a wide range of silicon-stereogenic silanes, is successfully developed. This process involves a SiH2-steered highly enantioselective C-H silylation to furnish the corresponding desymmetric monohydrosilanes, which are subsequently trapped with alkenes in a stereospecific fashion to build functionally diverse asymmetrically tetrasubstituted silanes. This general strategy combines readily available dihydrosilanes and alkenes to construct various enantioenriched silicon-stereogenic silanes, including 9-silafluorenes, Si-bridged ladder compounds, and benzosilolometallocenes, in a single step with good to excellent yields and enantioselectivities.

Tandem Rh(III)-Catalyzed C-H Heteroarylation of Indolyl Ketones and Cu(II)-Promoted Intramolecular Cyclization: One-Pot Access to Blue-Emitting Phenanthrone-Type Polyheterocycles.

Disclosed herein is a highly efficient one-pot synthetic strategy to phenanthrone-type polyheterocycles via tandem rhodium(III)-catalyzed ortho-C-H heteroarylation of indolyl ketones and copper(II)-promoted intramolecular cyclization. This protocol enables a library of blue-emitting fluorophores with high quantum yields and narrow full widths at half-maximum to be rapidly built from readily available substrates, among of which 6,6,7,9,12-pentamethyl-6,12-dihydro-5 H-benzofuro[2,3- a]carbazol-5-one (4a) exhibits pure blue emission with Commission Internationale de I'Eclairage coordinates of (0.15, 0.09) and a high quantum yield of 85% in CH2Cl2 solution.

Iridium-Catalyzed Direct Regioselective C4-Amidation of Indoles under Mild Conditions.

An efficient Ir-catalyzed amidation of indoles with sulfonyl azides is disclosed, affording diverse C4-amidated indoles exclusively under mild conditions. In this protocol, a variety of indoles with commonly occurring functional groups such as formyl, acetyl, carboxyl, amide, and ester at the C3 position are well tolerated.

Rhodium-catalyzed direct annulation of aldehydes with alkynes leading to indenones: proceeding through in situ directing group formation and removal.

The Rh-catalyzed direct annulation of an aldehyde with an alkyne leading to indenone was achieved. The in situ temporal installation of acetylhydrazine enables the annulation of the ortho arene C-H bond with alkynes to form ketone hydrazone. Subsequently, the in situ directing group removal takes place since ketone hydrazone is more susceptible toward hydrolysis than aldehyde hydrazone. Notably, this procedure tolerates a series of functional groups, such as methoxyl, acetylamino, fluoro, trifluoromethyl, methoxycarbonyl, chloro, and bromo groups.