Asymmetric synthesis of (+)-stagonolide C and (−)-aspinolide A via organocatalysis

Organocatalytic Asymmetric Epoxidation and Aziridination of Olefins and Their Synthetic Applications

“…In the syntheses of (−)-aspinolide A ( 163 ) and (+)-stagonolide C ( 166 ) reported by Suryavanshi, Sudalai, and co-workers, epoxy alcohols 162 and 165 were obtained in 99% ee from the corresponding enals via epoxidation with catalyst 137 and subsequent reduction with NaBH 4 (Scheme ) …”

Chemoenzymatic Total Synthesis of the Proposed Structures of Putaminoxins B and D

“…Unfortunately, the data mismatch with putaminoxin (5 S ,9 R )- 8 (Figure C,D and for further information Table S4.6), whereas its total syntheses confirmed the (5 S ,9 R )-configuration. ,, In addition, the data of the other diastereomer (5 S ,9 S )- 7 correspond well to the signals of the natural product aspinolide A (5 R ,9 R )-( 19 ) (Figure E,F), whereas the spectra of its diastereomer stagonolide F (5 S ,9 R )- 19 do not (Figure G,H). Nevertheless, the absolute configurations of aspinolide A and stagonolide F were also confirmed by several syntheses. − Comparing the specific rotations, it appears that the configuration on C-9 has a higher influence, resulting in a negative value in case of a (9 R )-configuration. The negative specific rotations of our synthesized compounds (5 S ,9 R )- and (5 R ,9 R )- 7 are in line with all other (9 R )-configured nonenolides.…”

An efficient organocatalytic route for asymmetric total synthesis of Stagonolide F

“…Carboxylic acid fragment 10 was obtained with an overall yield of 15.1% in 98% ee, determined by comparing its specific rotation with the reported value [α] D 25 +6.5 (c 1.0, CHCl 3 ) {lit. 3 [α] D 25 +6.6 (c 1.15, CHCl 3 )}…”

“…In continuation of our programme towards the total synthesis of biologically active natural products containing lactone moiety, we have recently described the total synthesis of Stagonolide C (2) and Aspinolide A (3). 3 Till date three synthetic routes have been documented in the literature for the synthesis of Stagonolide F (1). 4 Rao et al 4a have achieved the first total synthesis of Stagonolide F (1) which relied on combination of Jacobsen's hydrolytic kinetic resolution (HKR) 5 and Sharpless asymmetric epoxidation 6 as the key steps for inducing chirality.…”