We report new procedures for stereoselective cyclopentene and cyclohexenone construction employing the alkylidene carbene C−H insertion reaction. Described are diastereoselective insertion into methylene and enantiospecific insertion into methine C−H bonds. The latter case leads directly to the enantioselective synthesis of (+)-cassiol (1).

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Preorganized pixel-forming photoresists were prepared to investigate the effect of well-defined material structures and the spatial distribution of photoacid on line edge roughness of chemically amplified photoresists. Asymmetric poly(styrene)-block-poly(t-butylacrylate) (PS-b-PtBA) diblock copolymers, which formed PS cylinders or spheres within a PtBA matrix, were used as photoresists by adding catalytic amounts of photoacid generators (PAGs). PAGs resided only in the PtBA matrix domain, resulting in the PAG chemistry occurring only in the matrix domain. The pixelated photoresists showed a significant solubility switch after UV or x-ray exposure and postexposure bake, such that the polymer in the exposed regions dissolved in aqueous base solution. Granular structures that were matched with the domain spacing and structure of the block copolymer photoresists were observed on the edge of the patterned features. This model system demonstrated that line edge roughness is directly correlated to the structure of pixelated photoresist materials.

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