We observe vibronic transitions in CaD + between the 1 1 Σ and 2 1 Σ electronic states by resonance enhanced multiphoton photodissociation spectroscopy in a Coulomb crystal. The vibronic transitions are compared with previous measurements on CaH + . The result is a revised assignment of the CaH + vibronic levels and a disagreement with CASPT2 theoretical calculations by approximately 700 cm −1 .

We measure the rovibronic transitions X Σ, v″ = 0, J″ → A Σ, v' = 0-3, J' of CaH and obtain rotational constants for the A Σ state. The spectrum is obtained using two-photon photodissociation of CaH cotrapped with Doppler cooled Ca. The excitation is driven by a mode-locked, frequency-doubled Ti:Sapph laser, which is then pulse shaped to narrow the spectral bandwidth. The measured values of the rotational constants are in agreement with ab initio theory.

Tetrahydrocarbazoles have been prepared in one‐flask syntheses from indoles, ketones or aldehydes, and maleimides, with acid catalysis. The reactions involve a condensation of the indole with the ketone or aldehyde, followed by an in situ trapping of the vinylindole in a Diels‐Alder addition with a maleimide. Isomerization of the double bond into the indole nucleus gave the tetrahydrocarbazoles which were isolated (6, 9, and 10). Variation of the indole, carbonyl compound, and maleimide has been explored. The predominant stereochemistry of the tetrahydro ring in the products is all‐cis, although a second stereoisomer has been isolated. Two regioisomers were generated from all unsymmetrical 2‐alkanones, except 2‐butanone, which gave the single isomer 9a. Aromatization of tetrahydrocarbazoles 6 to carbazoles 7 was accomplished with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone.

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