Abstract:
:The epimeric diterpenes (+)-(1S,3E,7E,11S,12S)-verticilla-3,7-dien-12-ol (1), isolated from Bursera suntui, and (+)-(1S,3E,7E,11S,12R)-verticilla-3,7-dien-12-ol (2), isolated from Bursera kerberi, gave the same Wagner-Meerwein rearrangement product (-)-(1E,4Z,8Z,11S,12R)-phomacta-1,(15)4,8-triene (3). The Et2 O:BF3 -induced transformations evidence that verticillenes and phomactanes, both containing the bicyclo[9.3.1]pentadecane skeleton, are biogenetically related through the verticillen-12-yl cation (A+ ), which also is a key intermediate in the biosynthetic pathways to generate antitumor taxanes. Molecular modeling using the Monte Carlo protocol, followed by density functional theory (DFT) geometry optimization employing the hybrid functionals B3LYP and B3PW91, both with the DGDZVP basis set, secured the configuration of 3 as followed from the good agreement between the calculated and experimental vibrational circular dichroism spectra. Similar DFT calculations allowed determining the absolute configuration of (+)-(1R,4R,5R,8S,9S,11S,12R,15R)-1,15:4,5:8,9-triepoxyphomactane (9), which surprisingly derives from epoxidation of the second minimum energy conformer of 3.
journal_name
Chiralityjournal_title
Chiralityauthors
Del Río-Chávez ÁA,García-Gutiérrez HA,Román-Marín LU,Beiza-Granados L,Cerda-García-Rojas CM,Joseph-Nathan P,Hernández-Hernández JDdoi
10.1002/chir.23061subject
Has Abstractpub_date
2019-11-01 00:00:00pages
934-946issue
11eissn
0899-0042issn
1520-636Xjournal_volume
31pub_type
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