Complimentary to classical hydroboration and boron-Wittig reactions, a new, efficient access to cyclic 1,3-dienyl boronic esters has been developed diene or triene metathesis. Subsequently, fused pyrroles were synthesized with a broad substrate scope from the reaction of cyclic 1,3-dienyl boronic esters with arylnitroso compounds using a one-pot hetero-Diels-Alder/ring contraction sequence.
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http://dx.doi.org/10.1021/acs.joc.9b03214 | DOI Listing |
Arch Biochem Biophys
June 1996
Department of Chemistry, University of Illinois, Urbana 61801, USA.
The biosynthesis of diterpene hydrocarbons with enzyme extracts from rice cell suspension cultures was investigated to verify proposed pathways and intermediates in the production of the momilactone and oryzalexin phytoalexins. Diterpene synthase activity in cells treated with chitin to elicit the phytoalexin response was compared with the activity in untreated cells using the acyclic substrates [1-3H](E,E,E)- and [1-3H] (E,Z,E)-geranylgeranyl diphosphates (GGPPs 4-OPP and 11-OPP) as well as the bicyclic substrates [15-3H]ent-copalyl and [15-3H] syn-copalyl diphosphates (CPPs, 5-OPP, and 6-OPP). ent-kaurene (7), ent-sanda, racopimaradiene (8), 9 beta H-pimara-7,15-diene (9), and stemar-13-ene (10) were identified as major products by comparisons with authentic standards.
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