Synthesis of Enantiopure Dehydropiperidinones from α-Amino Acids and Alkynes via Azetidin-3-ones

Chiral dehydropiperidinones were synthesized in enantiopure form from α-amino acids and alkynes via azetidin-3-ones

Cleavage of C–C and C–Si σ‑Bonds and Their Intramolecular Exchange

C–C and C–Si σ-bonds are cleaved to undergo bond exchange when substrates equipped with cyclobutanone and silacyclobutane moieties are treated with a palladium(0) catalyst. The skeletal exchange results in construction of silabicyclo[5.2.1]­decanes in a diastereoselective manner

Palladium-Catalyzed Intramolecular Insertion of Alkenes into the Carbon–Nitrogen Bond of β‑Lactams

The carbon–nitrogen bond of β-lactams is cleaved by palladium(0), and an alkene is intramolecularly inserted therein. The following reductive elimination produces nitrogen-containing benzo-fused tricycles in good to high yields

Construction of Homoallylic Alcohols from Terminal Alkynes and Aldehydes with Installation of <i>syn</i>-Stereochemistry

A cationic rhodium­(I) catalyst turns 2-silyl-1-alkenyl­boronate, readily prepared from a terminal alkyne, into the corresponding allylboronate species, which immediately undergoes nucleophilic addition to an aldehyde to give a <i>syn</i>-homoallylic alcohol stereoselectively

Synthesis of Penta-2,4-dien-1-imines and 1,2-Dihydropyridines by Rhodium-Catalyzed Reaction of <i>N</i>‑Sulfonyl-1,2,3-triazoles with 2‑(Siloxy)furans

A rhodium­(II)-catalyzed reaction of <i>N</i>-sulfonyl-1,2,3-triazoles with 2-(siloxy)­furans is reported. Either open-chain penta-2,4-dien-1-imines or cyclic 1,2-dihydropyridines are selectively obtained depending on the ligand on rhodium­(II)

Light-Driven Carboxylation of <i>o</i>‑Alkylphenyl Ketones with CO₂

<i>o</i>-Alkylphenyl ketones undergo a C–C bond forming carboxylation reaction with CO₂ simply upon irradiation with UV light or even solar light. The reaction presents a clean process exploiting light energy as the driving force for carboxylation of organic molecules with CO₂

Copper-Catalyzed Amination of Silyl Ketene Acetals with <i>N</i>‑Chloroamines

A copper(I)/2,2′-bipyridyl complex catalyzes an amination reaction of silyl ketene acetals with <i>N</i>-chloroamines, presenting a new preparative method of α-amino esters

Enantioselective Insertion of a Carbenoid Carbon into a C–C Bond To Expand Cyclobutanols to Cyclopentanols

When a carbenoid species generated from a tosylhydrazone is reacted with a cyclobutanol in the presence of a chiral rhodium catalyst, a C–C single bond of the cyclobutanol is cleaved, and the carbenoid carbon is inserted therein to furnish a ring-expanded cyclopentanol in an enantioselective manner

Intramolecular Dearomatizing [3 + 2] Annulation of α‑Imino Carbenoids with Aryl Rings Furnishing 3,4-Fused Indole Skeletons

The rhodium-catalyzed dearomatizing [3 + 2] annulation reaction of 4-(3-arylpropyl)-1,2,3-triazoles is described. It provides a straightforward synthetic pathway from simple 5-aryl-1-alkynes leading to tricyclic 3,4-fused dihydroindoles via the corresponding 1,2,3-triazoles

sp³–sp² vs sp³–sp³ C–C Site Selectivity in Rh-Catalyzed Ring Opening of Benzocyclobutenol: A DFT Study

The C_sp³–C_sp² vs C_sp³–C_sp³ site selectivity in the C–C bond activation in Rh-catalyzed ring opening of benzocyclobutenol was systematically investigated using density functional theory (DFT). The catalytic cycle includes three elementary steps: the proton transfer from the substrate to a rhodium hydroxide, the C–C cleavage, and the proton transfer from water onto a carbon forming the final product with regeneration of the rhodium hydroxide. The site selectivity is determined by the C–C cleavage step; the C_sp³–C_sp² cleavage is favored over the C_sp³–C_sp³ cleavage because the former transition state is stabilized by an interaction between the benzene ring of the substrate and Rh. DMSO, a more polar solvent, reduces the site selectivity as the more polar C_sp³–C_sp³ transition state (TS) is stabilized more than the C_sp³–C_sp² TS and decreases the advantage of the latter TS. DPPF ligand is bulky, and the steric repulsion on the tighter C_sp³–C_sp² TS causes the loss of the site selectivity. For the even more crowded Rh­(P­(<i>t</i>-Bu)₃)₂ catalyst, one phosphine has to dissociate before the C–C cleavage reaction takes place, and the advantage of the C_sp³–C_sp² TS is regained for the less crowded RhP­(<i>t</i>-Bu)₃ active catalyst