0000000000077673
AUTHOR
Victoria Bargues
Stereoselective Synthesis of (+)-11βH,13-Dihydroestafiatin, (+)-11βH,13-Dihydroludartin, (−)-Compressanolide, and (−)-11βH,13-Dihydromicheliolide from Santonin
Starting from 2 and 3, obtained from santonin (1), we have synthesized natural guaianolides 4-7. Chemoselective epoxidation of 2 gave (+)-11betaH,13-dihydroestafiatin (4), and epoxidation of 3 followed by regioselective elimination of the hydroxyl group afforded (+)-11betaH,13-dihydroludartin (5). Sharpless' mild regioselective ring-opening of 4 and 5 followed by hydrogenolysis yielded (-)-compressanolide (6) and (-)-11betaH,13-dihydromicheliolide (7), respectively.
ChemInform Abstract: Stereoselective Synthesis of 7,11-Guaien-8,12-olides from Santonin. Synthesis of Podoandin and (+)-Zedolactone A.
Photochemical rearrangement of hydroxy ester 2, easily obtained from santonin (1), afforded butenolide 4, a good starting material for the synthesis of 7,11-guaien-8,12-olides. Compound 4 has been transformed into compound 10, which has been used for the synthesis of podoandin (5) and (+)-zedolactone A (ent-6). Regioselective elimination of the acetyl group on C10 afforded directly podoandin (5). For the synthesis of ent-6, a hydroxyl group has been regio- and stereoselectively introduced at the 4α-position through the 3α,4α-epoxide 15. The basic hydrolysis of the 10-acetyl group in compound 18 took place with concomitant intramolecular conjugated addition of the alkoxide to the butenolide …
Ultrasound assisted reductive cleavage of eudesmane and guaiane γ-enonelactones. Synthesis of 1α,7α,10αH-guaian-4,11-dien-3-one and hydrocolorenone from santonin
Abstract Ultrasound enhances the rate of reductive cleavage of the C6–oxygen bond of sesquiterpene enonelactones. trans-Eudesmanolides 1c–1g, cis-eudesmanolides 2a–2c, and trans-guaianolides 4a–4d react with Zn in acetic acid–H2O under sonochemical conditions to afford the corresponding sesquiterpene acids 3a–3g and 5a–5d, respectively in good yields. Starting from 5d two natural guaianes 1α,7α,10αH-guaian-4,11-dien-3-one (6) and hydrocolorenone (7) have been prepared in good yields through a straightforward sequence.
Stereoselective synthesis of 7,11-guaien-8,12-olides from santonin. Synthesis of podoandin and (+)-zedolactone A.
Photochemical rearrangement of hydroxy ester 2, easily obtained from santonin (1), afforded butenolide 4, a good starting material for the synthesis of 7,11-guaien-8,12-olides. Compound 4 has been transformed into compound 10, which has been used for the synthesis of podoandin (5) and (+)-zedolactone A (ent-6). Regioselective elimination of the acetyl group on C10 afforded directly podoandin (5). For the synthesis of ent-6, a hydroxyl group has been regio- and stereoselectively introduced at the 4alpha-position through the 3alpha,4alpha-epoxide 15. The basic hydrolysis of the 10-acetyl group in compound 18 took place with concomitant intramolecular conjugated addition of the alkoxide to the…
Ultrasound assisted reductive cleavage of sesquiterpene γ-enonelactones
Abstract Ultrasound enhances the rate of reductive cleavage of the C 6 -oxygen bond of several cis - and trans - sesquiterpene γ-enonelactones. Interestingly ultrasound overrides the stereoelectronic requirements for the reductive cleavage of the most usually occurring sesquiterpene trans -lactones.
Regio- and stereoselective oxyfunctionalization at C-1 and C-5 in sesquiterpene guaianolides
Abstract The regio- and stereoselective functionalization at C-1 and C-5 positions in a guaiane skeleton by allylic hydroxylation are described. The stereochemistry of the resulting compounds are identical to those of the majority of natural 1- and 5-hydroxy-guaianolides.
ChemInform Abstract: Ultrasound-Assisted Reductive Cleavage of Eudesmane and Guaiane γ-Enonelactones. Synthesis of 1α,7α,10αH-Guaian-4,11-dien-3-one and Hydrocolorenone from Santonin.
Abstract Ultrasound enhances the rate of reductive cleavage of the C6–oxygen bond of sesquiterpene enonelactones. trans-Eudesmanolides 1c–1g, cis-eudesmanolides 2a–2c, and trans-guaianolides 4a–4d react with Zn in acetic acid–H2O under sonochemical conditions to afford the corresponding sesquiterpene acids 3a–3g and 5a–5d, respectively in good yields. Starting from 5d two natural guaianes 1α,7α,10αH-guaian-4,11-dien-3-one (6) and hydrocolorenone (7) have been prepared in good yields through a straightforward sequence.
ChemInform Abstract: Ultrasound-Assisted Reductive Cleavage of Sesquiterpene γ- Enonelactones.
Abstract Ultrasound enhances the rate of reductive cleavage of the C 6 -oxygen bond of several cis - and trans - sesquiterpene γ-enonelactones. Interestingly ultrasound overrides the stereoelectronic requirements for the reductive cleavage of the most usually occurring sesquiterpene trans -lactones.
Synthesis of 9-oxyfunctionalized eudesmanes from artemisin
Abstract Artemisin ( 1 ) was transformed into two natural sesquiterpenoids 2 and 3 in a sequence which involves functionality transfer from C 8 to C 9 and further elaboration of the A ring and the lactone moiety.