We report a new, highly diastereoselective method for the synthesis of strained 5,5,6-fused tricyclic γ-lactones via a palladium-catalyzed tandem Heck/Suzuki cross-coupling reaction, followed by epoxidation and lactone-forming epoxide opening. Using this sequence, we prepared tricyclic γ-lactones with three consecutive stereocenters from simple, readily available starting materials, including one derived from enantiomerically pure biomass-based levoglucosenone. Our method provides a stereocontrolled approach to complex scaffolds of potential relevance in synthetic and medicinal chemistry.

A new protocol for the Pd-catalyzed hydroalkoxylation of alkoxyallene is presented that proceeds under strongly basic conditions. Notably, this method accommodates sterically hindered tertiary alcohols and carbohydrate-derived alcohols, which proved unreactive under the previous base-free conditions. This result was rationalized by the outer-sphere addition of alkoxide nucleophile to the syn π-allyl complex. Synthetic utility of the reaction was demonstrated by convergent synthesis of [1,4]-linked pentasaccharide.

In this work, we describe the synthesis of a new class of chiral thiourea catalysts that feature a reactivity-enhancing pyridine group and a fluxional substituent that impacts selectivity. The synthesis of the chiral catalysts, which is modular, can be accomplished in four steps with good yields. We have evaluated the efficacy of the new catalysts in the conjugate addition of indoles to fluoroalkyl nitroalkenes. The reactions provide a variety of fluorinated chiral building blocks in 65-99% yield with 81-91% ee.

Aminobenzisoxazoles are important scaffolds in medicinal chemistry. Traditionally, these heterocycles have been synthesized from 2-fluorobenzonitriles and N-protected hydroxylamines via the SNAr reaction and subsequent cyclization. We have developed a novel, orthogonal method that utilizes 2-hydroxybenzonitriles with O-(diphenylphosphoryl)hydroxyl amine as an electrophilic nitrogen source. This approach inverts the traditional polarity (making the arene the nucleophile) and allows for mild reaction conditions, a broad substrate scope, and extension to a few other heterocycles.

Existing BN-doped fluoranthenes are typically peripheral dopants with blue-shifted emission and loose intermolecular interactions. Herein, we strategically engineer internal BN doping in symmetric fluoranthene analogues that induces a pronounced red-shift in emission and directional B···π/B···B interactions. This molecular design enables enhanced orbital overlap through tight π-π stacking, yielding an outstanding hole mobility of 0.8 cm2 V-1 s-1 in organic field-effect transistors. This work culminates in the first successful application of BN-doped fluoranthene.

The enantioselective addition of masked acyl cyanide (MAC) to isatin is a highly efficient strategy for synthesizing bioactive chiral spirooxindoles. Herein, we report the utility of this strategy in an asymmetric total synthesis of (S)-(-)-dioxibrassinin and (R)-(+)-spirobrassinin, which are well-known phytoalexin alkaloids present in Brassicaceae plants. We developed a bifunctional monothiosquaramide (9b)-catalyzed addition of MAC to isatin, affording chiral oxindole esters (11a-11j) with excellent enantioselectivities (>99% ee) under mild conditions and catalyst loadings around 10 mol %. We accomplished the total synthesis of (S)-(-)-dioxibrassinin (1) and (R)-(+)-spirobrassinin (2) from oxindole ester 11a in a few subsequent steps with high overall yields (65%) and selectivities (99% ee).

We report the first hydrothiocarbonylation of (un)activated alkynes using bench-stable 1,4-DHP thioester surrogates under photochemical conditions, enabling a general route to (E)-α,β-unsaturated thioesters with excellent regio- and stereoselectivity. A Pd/photoredox catalytic system facilitates DHP thioester activation and site-selective hydrocarbonylation while controlling photoisomerization and side reactions. Moreover, a combination of benzil and boron Lewis acid pairs promotes E-to-Z photoisomerization, accessing (Z)-α,β-unsaturated thioester.

Benzannulation strategies that attach a planar arene ring to cyclic, saturated, three-dimensional bridged motifs are becoming valuable for drug discovery. Herein, a Lewis acid-catalyzed [4+3] annulation of in situ-generated o-QMs with bicyclo[1.1.0]butanes is developed. Reaction modulation further leveraged a telescoped [4+2] annulation of o-QMs with the in situ-formed cyclobutanes, leading to diversified sp3-rich oxabicyclic architectures. Overall, this study expands the scope for a new bioisosteric space for medicinal chemistry.

A general and operationally simple method for removing substituents from tertiary amines via Michael-addition-triggered carbocation release is described. Using methyl propiolate, hexafluoroisopropyl alcohol (HFIP), and thioanisole, this reaction enables efficient, metal-free cleavage of challenging groups─including benzyl, p-methoxybenzyl (PMB), allyl, propargyl, diphenylmethyl, and tert-butyl. This carbocation-mediated platform offers predictable, broad-scope amine deprotection and provides a practical alternative to hydrogenolysis and other redox-based protocols.

We report a concise two-step synthesis of the elusive heptacene isomer dibenzo[a,o]picene via regioselective Mallory photocyclization of a bis(stilbenyl)phenanthrene precursor. DFT calculations rationalize the observed regioselectivity and confirm the aromatic, highly stable framework. Dibenzo[a,o]picene exhibits a 2.98 eV optical band gap, reversible oxidation, and a low-lying HOMO. Single-crystal X-ray analysis reveals one-dimensional π-stacking (3.31 Å). Single-crystal OFETs display p-type hole mobilities of 3.2 × 10-3 cm2 V-1 s-1, establishing this long-sought isomer as a promising air-stable semiconductor.