Absolute Konfiguration der enantiomeren α-CyclogeraniumsäUren, α-Cyclogeraniale, α-Jonone, γ-Jonone, α-und ϵ-Carotine

By chemical correlation with manool and ambrein the absolute configurations of the enantiomeric α-cyclogeranic acids, α-cyclogeranials, α-ionones and α- and ?-carotenes have been elucidated.     

17‐Oxo‐5α‐androstane‐3α,4β‐diyl diacetate and 17‐oxo‐5β‐androstane‐3α,4β‐diyl diacetate

The title compounds, both C₂₃H₃₄O₅, are the 5α and 5β configurations of two diacetate epimers. The 5β‐diacetate crystallizes in an hexagonal structure, unusual for steroid molecules. The unit cell has an accessible solvent volume of 358 ų, responsible for clathrate behaviour. The 5β‐epimer also features some shorter than average bond lengths in the 3α,4β‐acetoxy groups. The conformations of the molecules of both epimers are compared with those obtained through abinitio quantum chemistry calculations. Cohesion of the crystals can be attributed to van der Waals and weak molecular C—H⋯O interactions.     

Photochemische Reaktionen. 56. Mitteilung [1]. Die Photoisomerisierung des α,β-ungesättigten δ-Diketons 3, 7-Dioxo-4, 4-dimethyl-17 β-acetoxy-δ5-androsten und dessen 3-Ketalderivates

On irradiation with light of wavelengths 2537 or > 3400 Å 4,4-dimethyl-17β-acetoxy-androst-5-ene-3, 7-dione ( 8 ) rearranges to the two diastereoisomeric products 9 and 10 . This isomerization is the only detectable photochemical reaction of 8 in a variety of solvents, including p-dioxane. Complete quenching with 0.5M naphthalene (on irradiation with > 3400 Å) indicates a triplet reaction. The photochemistry of the 3-ethylene ketal derivative 29 differs completely. Irradiation in p-dioxane solution leads exclusively to photoreduction and formation of the four diastereoisomeric dioxanyl allyl tert.-carbinols 30a – d .