The 235-360 GHz Rotational Spectrum of 1-Oxaspiro[2.5]octa-4,7-dien-6-one─Analysis of the Ground Vibrational State and Its 10 Lowest-Energy Vibrationally Excited States.

The millimeter-wave rotational spectrum of 1-oxaspiro[2.5]octa-4,7-dien-6-one (1) was collected from 235 to 360 GHz. With the rotational spectrum of this compound available for the first time, more than 5500 a- and c-type transitions were observed and assigned for the vibrational ground state. These transitions were least-squares fit to S- and A-reduced, sextic distorted-rotor Hamiltonians in the Ir representation (σfit = 37 kHz). Additionally, transitions of four fundamental states (ν22, ν21, ν39, and ν38), four overtone states (2ν22, 3ν22, 4ν22, and 5ν22), and two combination states (ν22 + ν21 and ν22 + ν39) were measured, assigned, and least-squares fit to single-state, S- and A-reduced, sextic distorted-rotor Hamiltonians in the Ir representation (σfit < 42 kHz). The computed vibration-rotation interaction constants (B0 - Bv) (MP2 and B3LYP/6-311+G(2d,p)) were compared to their corresponding experimental values, showing excellent agreement for all fundamental states. Based on the intensities of the transitions from six members of the v ν22 series, the fundamental frequency of ν22 was determined to be 79.0 (2.1) cm-1.

DNA-Compatible Copper/TEMPO Oxidation for DNA-Encoded Libraries.

Aldehydes are important synthons for DNA-encoded library (DEL) construction, but the development of a DNA-compatible method for the oxidation of alcohols to aldehydes remains a significant challenge in the field of DEL chemistry. We report that a copper/TEMPO catalyst system enables the solution-phase DNA-compatible oxidation of DNA-linked primary activated alcohols to aldehydes. The semiaqueous, room-temperature reaction conditions afford oxidation of benzylic, heterobenzylic, and allylic alcohols in high yield, with DNA compatibility verified by mass spectrometry, qPCR, Sanger sequencing, and ligation assays. Subsequent transformations of the resulting aldehydes demonstrate the potential of this method for robust library diversification.

DNA-Scaffolded Synergistic Catalysis.

We report DNA-scaffolded synergistic catalysis, a concept that combines the diverse reaction scope of synergistic catalysis with the ability of DNA to precisely preorganize abiotic groups and undergo stimuli-triggered conformational changes. As an initial demonstration of this concept, we focus on Cu-TEMPO-catalyzed aerobic alcohol oxidation, using DNA as a scaffold to hold a copper cocatalyst and an organic radical cocatalyst (TEMPO) in proximity. The DNA-scaffolded catalyst maintained a high turnover number upon dilution and exhibited 190-fold improvement in catalyst turnover number relative to the unscaffolded cocatalysts. By incorporating the cocatalysts into a DNA hairpin-containing scaffold, we demonstrate that the rate of the synergistic catalytic reaction can be controlled through a reversible DNA conformational change that alters the distance between the cocatalysts. This work demonstrates the compatibility of synergistic catalytic reactions with DNA scaffolding, opening future avenues in reaction discovery, sensing, responsive materials, and chemical biology.