4,6,8,10,16-Penta- and 4,6,8,10,16,18-Hexamethyldocosanes from the Cane Beetle Antitrogus parvulus - Cuticular Hydrocarbons with Unprecedented Structure and Stereochemistry

Abstract

The major cuticular hydrocarbons from the cane beetle species Antitrogus parvulus were deduced to be 4,6,8,10,16,18-hexa- and 4,6,8,10,16-pentamethyldocosanes 2 and 3, respectively. Isomers of 2,4,6,8-tetramethylundecanal 27, 36, and 37, derived from 2,4,6-trimethylphenol, were coupled with the phosphoranes 28 and 29 to furnish alkenes and, by reduction, diastereomers of 2 and 3. Chromatographic and spectroscopic comparisons confirmed 2 as either 6a or 6b and 3 as either 34a or 34b. [structure: see text]

Total synthesis of the cytotoxic cyclodepsipeptide (-)-doliculide: The “ester” effect in acyclic 1,3-induction of deoxypropionates

“…The stereochemical identity of 9 was rigorously established from detailed NMR studies of syn͞syn and syn͞anti isomers as their two-carbon homologated enoates (60). 13 C inverse gated analysis of characteristic signals proved to be an excellent direct method for assessing diastereomeric ratios of cuprate adducts in this series (see Supporting Materials and Methods, which is published as supporting information on the PNAS web site). Thus, a 14-step, highly stereocontrolled synthesis of the advanced intermediate 9 from L-gulonic ␥-lactone was in hand for further elaboration to the intended final target.…”

“…Thus, reduction of 13 with L-Selectride proceeded in good yield, but the desired C 9 alcohol was obtained as the minor isomer (syn͞anti, 4:1). The relative configuration of the alcohol at C 9 was established based on 13 C resonance shifts as suggested by Hoffmann and Weidmann (69) for related compounds.…”

“…Natural products that contain multiple deoxypropionate units are comparatively fewer and are generally characterized by an all-syn orientation of methyl groups on an acyclic framework, as in the structures of lardolure (7), siphonarienal (6), siphonarienolone (8), pectinatone (9,10), TMC-151 (11), and branched alkanoic acids isolated from the preen-gland wax of the domestic goose (12). A major cuticular hydrocarbon from a cane beetle species was reported recently to have an unprecedented three sets of anti-disposed deoxypropionates (13).…”

Making Mixtures to Solve Structures: Structural Elucidation via Combinatorial Synthesis

“…Synthetic Strategy. The total or partial synthesis of polypropylene oligomers 35,36 and natural products [37][38][39][40][41][42] containing C 3 repeat units like those in the target molecules has been reported previously. While natural products might be suitable precursors to series 3, 5, and 6, they are not readily amenable to the synthesis of the other target compounds; accordingly we opted for total synthesis.…”

Systematic Comparison of Sets of 13C NMR Spectra That Are Potentially Identical. Confirmation of the Configuration of a Cuticular Hydrocarbon from the Cane Beetle Antitrogus parvulus

“…1 The compounds were identified as a 4,6,8,10,16,18-hexamethyldocosane and a 4,6,8,10,16-pentamethyldocosane (Figure 1), and synthesis established the anti , anti , anti -orientation of the methyl groups at the 4,6,8,10-positions for both compounds.…”