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The application of dirhodium(II) caprolactamate as an efficient engine for the production of the tert-butylperoxy radical and selective reagent for hydrogen atom abstraction is demonstrated. The mechanistic implications arising from studies of allylic oxidation with enones provide new insights into factors that control product formation.

The selective C-H oxidation of alkynes to propargylic ketones was performed by using dirhohdium caprolactamate ([Rh.sub.2][(cap).sub.4]) with 70 percent w/w aqueous tert-butyl hydroperoxide as a highly effective catalytic oxidation protocol. The oxidation in aqueous solvent under mild condition with yields about 80 percent of [alpha],[beta]-acetylenic carbonyl compounds was found.

Dirhodium(II) caprolactamate (1, Rh2(cap)4) with 70% w/w aqueous tert-butyl hydroperoxide (T-HYDRO) is a highly effective catalytic oxidation protocol for the selective C-H oxidation of alkynes to propargylic ketones. The oxidation occurs readily in aqueous solvent under mild conditions with an inexpensive and easily handled oxidant. α,β-Acetylenic carbonyl compounds are formed in up to 80% isolated yield. [ABSTRACT FROM AUTHOR]

[Reaction: see text] Intramolecular photocycloaddition of 4 leads to the formation of cyclobutene photoadduct 5. Secondary photoreaction of 5 then affords either cyclobutane 19 or the bridged product 7, as a function of R (H or TMS).

[reaction: see text] A synthesis of 28, the carbon framework of the eleutherobin aglycone, is reported in a 15-step sequence from readily available starting materials. The tandem Diels-Alder reaction of 6 and 7 to produce 18, in which three new rings and six new stereocenters are formed, is a key step in the reaction sequence.