Efficient Conversion of Aucubin into 6-epi-Aucubin

Abstract

Selective deprotection of peracetylaucubin (3) by use of KCN led to 6-O-acetylaucubin (4), which was readily converted into 2',3',4',6', 10-penta-O-benzoylaucubin (7). Configuration inversion performed on 7, using a modified Mitsunobu reaction, followed by deprotection, afforded 6-epi-aucubin (2).

Influence of solvents and catalysts on the formation and hydrolysis of polyfunctional enoxysilanes derived from aucubin

“…In addition to the loss of one pivaloyl group, a quaternary carbon at 63.4 ppm was attributed to C-8 by a 3 J-HMBC correlation with H-1. The presence of the double bond Δ6-7 was shown firstly by the 13 C NMR chemical shifts at δ 145.1 and 130.2 ppm together with COSY correlation between H-7 at δ 5.66 ppm and H-6 at δ 6.51 ppm. Moreover HMBC correlations H-7/C-8', H-7/C-5a, H-6/C-8 and H-6/C-5a confirmed the insaturation's position.…”

“…Grimshaw in 1960, 4 this naturally occurring material devoid of cytotoxic activity, [5][6][7] is used for several decades by organic chemists for the synthesis of chiral building blocks or scaffolds. [8][9][10][11][12][13][14][15][16] Aucubin permitted the synthesis of various classes of biologically interesting chiral compounds: insect antifeedants, 17 carbocyclic nucleoside analogues, cytotoxic cyclopentenone glucosides, [21][22] chiral rigid -amino acid glucosides 23 and polyaminoiridoids whose have similar polarity with aminoside antibiotics. 24 For those syntheses, functional or skeletal modifications were applied to aucubin and sometimes with an innovative chemistry.…”

A novel series of cytotoxic iridoid glucosides derived from aucubin: Design, synthesis and structure–activity relationships

“…Indeed,under Birch conditions [25a], the selective reduction of allylic alcohol of 1 by Li/NH 3 , permitted the obtainment of linaride (10-deoxyaucubin, 8) when the reaction was conducted at À78 C and 6,10-deoxyaucubin (9) when the reaction was conducted at À40 C [25]. In order to prepare 6-O-acetyllinaride (10), peracetyllinaride (11) [25b], quantitatively obtained from 8 by acetylation, was selectively deacetylated using a procedure initially described in the sugar chemistry and previously applied in our group to the selective deacetylation of peracetylaucubin [16,18,26]. Thus, treatment of 11 with a catalytic amount of potassium cyanide, in a 2:1 anhydrous mixture of CH 3 OH and CH 2 Cl 2 , for 3 h at 20 C, gave 10 in 48% yield, accompanied by fully deprotected linaride (8), which could be easily separated from the reaction mixture and recycled.…”

Synthesis and Cytotoxicity of a Novel Iridoid Glucoside Derived from Aucubin

“…In continuation of our work on chiral-pool syntheses starting from aucubin (1) [5] [8], we now report the preparation and cytotoxic activity of the new aucubin analogue 2. This iridoid glucoside was designed to include the conjugated cyclopentenone pharmacophore considered to be responsible for antitumor activity of several oxylipins such as the natural clavulones [9] and clavirins, e.g., 3 [10], as well as the prostaglandin-based synthetic drug Tei 9826 ( methyl (7E)-9-oxoprosta-7,10-dien-1-oate; 4), which is currently under preclinical development [11].…”