Palladium-catalyzed hydrodehalogenation of butenolides: An efficient and sustainable access to β-arylbutenolides

Synthesis of Natural Rubrolides B, I, K, L, M, O and Analogues

“…With the β‐aryl butenolides 13 – 15 in hand, a vinylogous aldol condensation between commercially available benzaldehyde derivatives 16 – 18 was employed in order to synthesize the naturally occurring rubrolides B 1 , I 2 , K 3 , L 4 , M 5 , O 6 and nine rubrolide analogues 19 – 27 . As reported previously, [11,13,14,15,18] the vinylogous aldol condensation was conducted in a three‐step one‐pot synthesis, using TBSOTf, DIPEA (a) or Et 3 N (b) as base depending on the desired derivative and CH 2 Cl 2 at 0 °C for 30 min in the first step. Afterwards, the p‐ hydroxy benzaldehyde derivative ( 16 , 17 or 18 ) is added to the reaction mixture and stirred for another 24 h at room temperature.…”

“…In order to achieve complete conversion towards the dibrominated product, the presence of water was crucial and therefore, a solvent mixture of CH 2 Cl 2 /water (6 : 1) was used. Also, the dichlorinated intermediate As reported previously, [11,13,14,15,18] the vinylogous aldol condensation was conducted in a three-step one-pot synthesis, using TBSOTf, DIPEA (a) or Et 3 N (b) as base depending on the desired derivative and CH 2 Cl 2 at 0°C for 30 min in the first step. Afterwards, the p-hydroxy benzaldehyde derivative (16, 17 or 18) is added to the reaction mixture and stirred for another 24 h at room temperature.…”

“…Some of the natural abundant rubrolides were already synthesized employing various protocols, [11–25] since the biological activities, especially of higher halogenated rubrolides, is considered promising for the discovery of novel antiinfective agents. Therefore, a robust and divergent synthetic protocol for the construction of a suitable substance library is highly desirable.…”

“…Most rubrolides contain brominated phenol groups, and some also have a chloro substituent in α-position of the furanone ring (Figure 1). Some of the natural abundant rubrolides were already synthesized employing various protocols, [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] since the biological activities, especially of higher halogenated rubrolides, is considered promising for the discovery of novel antiinfective agents. Therefore, a robust and divergent synthetic protocol for the construction of a suitable substance library is highly desirable.…”

Synthesis of new tetronamides displaying inhibitory activity against bloom‐forming cyanobacteria

“…Conjugate addition of substituted anilines to commercially available α,β‐dichlorobutenolide ( 11a ) or α,β‐dibromobutenolide ( 11b ), followed by in situ β‐elimination, afforded intermediates 8a‐h and 8j in high yields . Submission of 8a to our reductive hydrodehalogenation procedure provided compound 8i in 66% yield (Scheme ).…”