Palladium(ii)-catalyzed C-C and C-O bond formation for the synthesis of C1-benzoyl isoquinolines from isoquinoline N-oxides and nitroalkenes

Fabrication of folded MXene/MoS2 composite microspheres with optimal composition and their microwave absorbing properties

In this work, ultrasonic spray technology is utilized for build up MXene and MoS₂ nanosheets to three-dimensional MXene/MoS₂ fold microspheres by one-step method. By skillfully assembling two kinds of functional two-dimensional materials, the microspheres have abundant heterogeneous interfaces and huge specific surface area. The optimum feed ratio of MXene and MoS₂ is determined by comparing the absorbing properties, and the mass ratio is 5:1. With 30% filler, the material shows the best absorption performance. At 10.4 GHz, the minimal reflection loss (RL_min) reach -51.21 dB, and the thickness is merely 2.5 mm. At the thickness in 1.6 mm, the efficacious absorption bandwidth (RL < -10 dB) reaches 4.4 GHz. The outstanding microwave absorbing properties with MXene/MoS₂ folded microspheres is resulted in the multiple interfaces in the heterostructure and above the average conductivity of MXene. The results show that MXene/MoS₂ folded microsphere is a prospective electromagnetic absorbing material. The construction of MXene/MoS₂ folded microsphere provides an effective method to devise new high-performance microwave absorbing materials.

A simple and efficient metal free, additive, or base free dehydrogenation of tetrahydroisoquinolines using oxygen as a clean oxidant

Metal free dehydrogenation of various substituted tetrahydroisoquinolines via a simple and convenient metal free, atom economical route for the synthesis of corresponding isoquinolines under oxygen atmosphere in N-methyl-2-pyrollidone (NMP) is described. Metal free dehydrogenation was carried out without the use of additive or base. A scope of the methodology was demonstrated for a number of aryl and heteroaryl substitutions present at C1 position and ester moiety at C3 position and was found to be good substrates. Substituted isoquinolines (3a–3h) and their esters (3i–3m) were synthesized in very good to excellent yields.

Synthesis of chromeno[4,3-b]quinolines and spirobenzofuran-3,3′-quinolines through silver-mediated Appel reaction/C–Br bond cleavage/double selective rearrangement sequence

A reduction and sequential silver-mediated Appel reaction/C–Br cleavage/double rearrangement cascade strategy was developed for the selective synthesis of chromeno[4,3-b]quinolines and spirobenzofuran-3,3′-quinolines.

Copper-Catalyzed Benign and Efficient Oxidation of Tetrahydroisoquinolines and Dihydroisoquinolines Using Air as a Clean Oxidant

A green chemical method for mild oxidation of 1,2,3,4-tetrahydroisoquinolines (THIQs) and 3,4-dihydroisoquinolines (DHIQs) has been developed using air (O₂) as a clean oxidant. DHIQs and THIQs could be efficiently oxidized to isoquinolines in dimethyl sulfoxide at 25 °C under an open air atmosphere with CuBr₂ (20 mol %) as the catalyst; different bases [NaOEt and/or 1,8-diazabicyclo[5,4,0]undec-7-ene] were used for the reaction according to the patterns of substituents (R¹, R²).

Oxidant-Controlled C-sp2/sp3-H Cross-Dehydrogenative Coupling of N-Heterocycles with Benzylamines

Oxidant controlled ionic liquid mediated cross-dehydrogenative coupling (CDC) of benzylamines with N-heterocycles having sp² or sp³ carbon resulted in the formation of C-benzoylated or alkenylated products. Benzoylation of N-heterocycles occurs via (NH₄)₂S₂O₈ catalyzed benzoyl radical formation. An oxidative alkenylation of N-heterocycles having C-sp³ carbon (2-methylaza-arenes) occurs via deamination of benzylamine followed by C-sp³-H bond activation in high stereoselectivity. Both benzoylation and alkenylation protocols are metal-free, green, simple, efficient, and tolerate a wide variety of functional groups.

Rh(III)-Catalyzed Aryl and Alkenyl C-H Bond Addition to Diverse Nitroalkenes

The transition metal catalyzed C-H bond addition to nitroalkenes has been developed. Very broad nitroalkene scope was observed for this Rh(III)-catalyzed method, including for aliphatic, aromatic and β,β-disubstituted derivatives. Additionally, various directing groups and both aromatic and alkenyl C-H bonds were effective in this transformation. Representative nitroalkane products were converted to dihydroisoquinolones and dihydropyridones in a single step and in high yield by iron mediated reduction and in situ cyclization. Moreover, preliminary success in enantioselective Rh(III)-catalyzed C-H bond addition to nitroalkenes was achieved as was X-ray structural characterization of a nitronate intermediate.