Enantioselective Synthesis of (E)‐δ‐Boryl‐Substituted anti‐Homoallylic Alcohols Using Palladium and a Chiral Phosphoric Acid

(E )‐δ‐Boryl‐substituted anti ‐homoallylic alcohols are synthesized in a highly diastereo‐ and enantioselective manner from 1,1‐di(boryl)alk‐3‐enes and aldehydes. Mechanistically, the reaction consists of 1) palladium‐catalyzed double‐bond transposition of the 1,1‐di(boryl)alk‐3‐enes to 1,1‐di(boryl)alk‐2‐enes, 2) chiral phosphoric acid catalyzed allylation of aldehydes, and 3) palladium‐catalyzed geometrical isomerization from the Z to E isomer. As a result, the configurations of two chiral centers and one double bond are all controlled with high selectivity in a single reaction vessel.     

Synthesis of γ‐Boryl‐Substituted Homoallylic Alcohols with anti Stereochemistry Based on a Double‐Bond Transposition

The stereoselective synthesis of anti isomers of γ‐boryl‐substituted homoallylic alcohols is disclosed. (E)‐1,2‐Di(boryl)alk‐1‐enes undergo Ru‐catalyzed double‐bond transposition with control of the geometry. The in situ generated (E)‐1,2‐di(boryl)alk‐2‐enes add to aldehydes in a stereospecific manner. The alkenylboron group within the product is amenable to a variety of synthetic derivatizations.     

Enantioselective Palladium‐Catalyzed Carbonylative Carbocyclization of Enallenes via Cross‐Dehydrogenative Coupling with Terminal Alkynes: Efficient Construction of α‐Chirality of Ketones

An enantioselective Pd^II/Brønsted acid‐catalyzed carbonylative carbocyclization of enallenes ending with a cross‐dehydrogenative coupling (CDC) with a terminal alkyne was developed. VAPOL phosphoric acid was found as the best co‐catalyst among the examined 28 chiral acids, for inducing the enantioselectivity of α‐chiral ketones. As a result, a number of chiral cyclopentenones were easily synthesized in good to excellent enantiomeric ratio with good yields.     

Synergistic Diastereo‐ and Enantioselective Functionalization of Unactivated Alkyl Quinolines with α,β‐Unsaturated Aldehydes

A novel alkyl functionalization of unactivated alkyl quinolines has been developed combining InCl₃ activation with organocatalytic activation of α,β‐unsaturated aldehydes in a synergistic fashion. The reaction proceeds in a highly stereoselective manner as a sequence involving two consecutive synergistic catalytic cycles (Lewis acid‐ and iminium ion‐catalyzed) and requires neither pre‐activated alkyl quinoline substrates with electron‐withdrawing substituents nor highly activated electrophiles. The reaction provides selectively double‐ or mono‐addition products in good yields and high to excellent stereoselectivities. Furthermore, based on spectroscopic and labelling experiments, the mechanisms for the reactions are discussed.     

Catalytic Enantioselective Assembly of Homoallylic Alcohols from Dienes,Aryldiazonium Salts,and Aldehydes

A highly selective multicomponent carbonyl allylation reaction of 1,3‐butadienes, aryldiazonium tetrafluoroborates, and aldehydes has been established under the combined catalysis of palladium acetate and chiral anion phase transfer to render the favorable assembly of chiral Z‐configured homoallylic alcohols in high yields and with excellent levels of enantioselectivity.     

Enantioselective Palladium‐Catalyzed Cross‐Coupling of α‐Bromo Carboxamides and Aryl Boronic Acids

We herein report an enantioselective palladium‐catalyzed cross‐coupling between α‐bromo carboxamides and aryl boronic acids, generating a series of chiral α‐aryl carboxamides in good yields and excellent enantioselectivities. The development of a chiral P,P=O ligand was critical in overcoming the second transmetalation issue and allows the first asymmetric palladium‐catalyzed coupling of α‐bromo carbonyl compounds.     

Enantioselective Rhodium‐Catalyzed Coupling of Arylboronic Acids, 1,3‐Enynes,and Imines by Alkenyl‐to‐Allyl 1,4‐Rhodium(I) Migration

A chiral rhodium complex catalyzes the highly enantioselective coupling of arylboronic acids, 1,3‐enynes, and imines to give homoallylic sulfamates. The key step is the generation of allylrhodium(I) species by alkenyl‐to‐allyl 1,4‐rhodium(I) migration.