Brønsted base-catalyzed imino-ene-type allylation reactions of simple alkenes as unactivated allyl compounds.

Catalytic imino-ene-type allylation reactions of unactivated allyl compounds were achieved. In the presence of a catalytic amount of a strongly basic KOtBu-LiTMP or NaOtBu-LiTMP mixed system, the desired reactions proceeded smoothly at low temperature. Notably, a gaseous alkene, propylene, could also be used in this reaction system.

Asymmetric C(sp3)-H functionalization of unactivated alkylarenes such as toluene enabled by chiral Brønsted base catalysts.

Benzylic functionalisation of unactivated alkylarenes remains as a significant challenge in asymmetric catalysis due to their less reactive nature. Here, we show development of catalytic asymmetric C(sp3)-H functionalization of unactivated alkylarenes such as toluene with imines. The reactions proceeded smoothly under proton-transfer conditions using a chiral, strong Brønsted base catalyst system. A chiral Brønsted base prepared from an alkylpotassium and a chiral amine ligand was found to effectively form a promising asymmetric environment around a benzyl anion. Optimization of the reaction conditions revealed that the use of the alkaline metal amide, potassium hexamethyldisilazide (KHMDS), as an additive was most effective, and enantioselective and atom economical carbon-carbon bond-forming reactions at the benzylic positions of unactivated alkylarenes was achieved without using any transition-metal catalyst.

Catalytic Direct-Type Addition Reactions of Alkylarenes with Imines and Alkenes.

Catalytic addition reactions of very weakly acidic nonactivated alkylarenes such as toluene and its derivatives were developed by using a strongly basic mixed catalyst system under mild reaction conditions. The addition reactions with imines and alkenes proceeded smoothly under proton-transfer conditions to afford the desired products in good to high yields, and high levels of regio- and stereoselectivity were achieved. It was also revealed that the asymmetric addition reaction of an alkylarene was possible.

Catalytic Asymmetric 1,4-Addition Reactions of Simple Alkylnitriles.

The development of catalytic asymmetric carbon-carbon bond-forming reactions of alkylnitriles that do not have an activating group at the α-position, under proton-transfer conditions, is a challenging research topic. Here, we report catalytic asymmetric direct-type 1,4-addition reactions of alkylnitriles with α,ß-unsaturated amides by using a catalytic amount of potassium hexamethyldisilazide (KHMDS) with a chiral macro crown ether. The desired reactions proceeded in high yields with good diastereo- and enantioselectivities. To our knowledge, this is the first example of catalytic asymmetric direct-type 1,4-addition reaction of alkylnitriles without any activating group at the α-position.

Catalytic asymmetric direct-type 1,4-addition reactions of simple amides.

The development of catalytic asymmetric direct-type reactions of less acidic carbonyl compounds such as amides and esters has been a challenging theme in organic chemistry for decades. Here we describe the asymmetric direct 1,4-addition reactions of simple amides with α,ß-unsaturated carbonyl compounds using a catalytic amount of a novel chiral catalyst consisting of a potassium base and a macrocyclic chiral crown ether. The desired 1,5-dicarbonyl compounds were obtained in high yields with excellent diastereo- and enantioselectivities. This is the first example of a highly enantioselective catalytic direct-type reaction of simple amides. In addition, the structure of the chiral potassium catalyst has been investigated by X-ray crystallographic, dynamic (1)H NMR, and MALDI-TOF MS analyses.