A Straightforward Protocol for One-Pot Allylic Aminations/Stille Couplings

Conjugated Mesopolymer Achieving 15% Efficiency Single-Junction Organic Solar Cells

The high-performance organic solar cells (OSCs) tend to choose the polymers with high molecular weight as donors, which easily produce good crystallinity to facilitate intermolecular charge transfer. However, these polymers usually accompanied by the low solubility and synthetic difficulty, increasing batch-to-batch variations. The proposal of conjugated mesopolymers (molar mass (M_n ) in 1-10 kDa) can overcome these problems. Herein, a new mesopolymer, MePBDFCl_H as donor material is designed and synthesized, and firstly applied in OSCs. As a comparison, other lower molecular weight mesopolymer of MePBDFCl_L and higher molecular weight polymer of PBDFCl with same structure are also prepared and investigated. Because of its appropriate phase separation and miscibility in the blend film, the MePBDFCl_H exhibits the highest power conversion efficiency (PCE) of 15.06% among the three materials. Meanwhile, the champion PCE is a new record for benzo[1,2-b:4,5-b']difuran-based photovoltaic materials. Importantly, comparing to the pronounced PCE decrease of polymer PBDFCl by about 12%, a slightly PCE difference for mespolymer MePBDFCl_L is only less than 5%, reducing the batch-to-batch variation. This work not only suggests that the benzo[1,2-b:4,5-b']difuran unit is a promising electron-donating core but also shows that the mesopolymers have great potentials to produce the low-differentiated and high-performance organic photovoltaic materials.

Palladium-catalyzed chemoselective allylic substitution, Suzuki-Miyaura cross-coupling, and allene formation of bifunctional 2-B(pin)-substituted allylic acetate derivatives

A formidable challenge at the forefront of organic synthesis is the control of chemoselectivity to enable the selective formation of diverse structural motifs from a readily available substrate class. Presented herein is a detailed study of chemoselectivity with palladium-based phosphane catalysts and readily available 2-B(pin)-substituted allylic acetates, benzoates, and carbonates. Depending on the choice of reagents, catalysts, and reaction conditions, 2-B(pin)-substituted allylic acetates and derivatives can be steered into one of three reaction manifolds: allylic substitution, Suzuki-Miyaura cross-coupling, or elimination to form allenes, all with excellent chemoselectivity. Studies on the chemoselectivity of Pd catalysts in their reactivity with boron-bearing allylic acetate derivatives led to the development of diverse and practical reactions with potential utility in synthetic organic chemistry.

Stannylated allyl carbonates as versatile building blocks for the diversity oriented synthesis of allylic amines and amides

Stannylated allylic carbonates are suitable substrates for Pd-catalyzed allylic aminations. In DMF and with [allylPdCl](2) as catalyst the stannylated allyl amines formed can be directly coupled with electrophiles according to the Stille protocol, giving rise to highly functionalized building blocks in excellent yields.