First stereoselective synthesis of synargentolide A and revision of absolute stereochemistry

An Efficient Stereoselective Total Synthesis of Synargentolide A and Its Epimer

“…The physical and spectral properties of these compounds were identical to those reported earlier [4]. Finally, the olefin cross-metathesis reaction of 3 and 9 with the known vinylsubstituted lactone 4 [5c] in the presence of Grubbs second-generation catalyst yielded the naturally occurring synargentolide A (1) and its epimer 2, respectively (Scheme 3).…”

“…Synargentolide A (1), a member of this group, was isolated from Syncolostemon argentees [2]. Compound 2 with the originally proposed structure of synargentolide A was synthesized by two research groups [3] [4], and one of the groups revised the structure of synargentolide A to 1 by synthesizing both 1 and 2 [4].…”

Tandem Ring‐Closing/Cross‐Metathesis Approach for the Synthesis of Synargentolide B and Its Stereoisomers

“…The structure of 2c was established based on the structure of 4deacetoxy-10-epi-olguine (6), [6] isolated from the same species. On the basis of the structures assigned to 2 and 2c, and our own structural revision (to 1b) of the originally proposed structure (i.e., 1a) of synargentolide A, [7] we undertook the synthesis of four diastereomers 2a-d differing in their relative configurations at C-5Ј and C-6Ј using a tandem ring-closing/cross-metathesis (RCM/CM) reaction as the key step, promoted by the second-generation Hoveyda-Grubbs catalyst. A (6R)-configuration was assigned based on the positive nǞπ* cotton effect in the CD spectrum.…”

Stereoselective total synthesis of lippialactone

“…Lippialactone (1) is structurally related to synargentolide A (2) (Figure 1), whose structure was revised by our team. 6 To date, however, only a single report has appeared on the synthesis of 1. 7 In continuation of our interest in the synthesis of bioactive natural δ-lactones, [8][9][10][11][12][13][14] we herein describe a stereoselective total synthesis of lippialactone.…”