Formolysis of protoilludyl cation equivalents a new mode of rearrangement of bicyclo[4.2.0]oct-2-yl cation

Pentalenene Synthase. Purification, Molecular Cloning, Sequencing, and High-Level Expression in Escherichia coli of a Terpenoid Cyclase from Streptomyces UC5319

“…50 mL on a rotatory evaporator at 0 °C, and an estimated one-fifth of the concentrate was used for GC-MS analysis on a Hewlett-Packard 5898 gas chromatograph mass spectrometer using a 12 m X 0.2 mm X 0.33 Mm thick crosslinked methyl silicone gum capillary column in electron ionization mode and a temperature program of 80-250 °C over 13 min. Enzymatically generated pentalenene (m/e 204) eluted at 5.99 min at a temperature of 158 °C and was identical in retention time and mass fragmentation pattern to authentic (i)-pentalenene2 (Cane & Tillman, 1983;Ohfune et al, 1976;Misumi et al, 1979).…”

Biosynthesis via carbocations: Theoretical studies on terpene formation

“…1) 36,49 and, to our knowledge, was the first dyotropic reaction proposed to occur in a biosynthetic context. Although an alternative energetically viable pathway to pentalenene (that involves a very unusual ''proton sandwich'' species 18 ) was also discussed, the observations that protoilludene can be formed in significant quantities from mutant pentalenene synthases 50 and that the cation precursor to protoilludene can rearrange in solution to form some pentalenene, 51 provide confidence in the viability of the mechanism shown in Fig. 6.…”

New Plant Growth Promoters, Repraesentins A, B and C, fromLactarius repraesentaneus

“…6) Compound 3 was similar to 2 in the 1 H-and 13 C-NMR spectra (Table 1), except for the presence of a carboxyl group (dC 182.8) and a secondary hydroxyl group (d C 72.2), and the absence of the primary hydroxyl group. The IR spectrum supported the presence of a carboxyl group (nmax 3600-2500 cm -1 ).…”