Synthesis of pentacyclic lα,11-(2-oxethano) steroids

Treatment of a 1α,2α-methyleneandrostan analog (4) with hydrobromic acid/acetic acid gives an apparent intramolecular homoconjugate ring-opening, which serves as the key step in the synthesis of a new type of pentacyclic steroid analogs (2).     

Enhanced structure determination of beta-pyrrole and N-substituted porphyrins by desorption chemical ionization mass spectrometry.

The extensive macrocycle—but minimal substituent—fragmentation occurring in the chemical ionization mass spectra of porphyrins when ammonia, rather than hydrogen, is the reagent gas leads to more detailed structure determinations.