Total Syntheses of Paraconic Acids and 1,10-seco-Guaianolides via a Barbier Allylation/Translactonization Cascade of 3-(Bromomethyl)-2(5H)-furanone

Competitive Delocalized Charge Transfer Boosted by Solvent Induction Strategy for Survivable Colorimetric Detection of ng-Level Urea

“…Principle of the Proposed Solvent Induction Strategy for Survivable Colorimetric Detection. It is known that aldehyde group (−CHO), comprised of the carbonyl with α-H, is a highly reactive atomic group in the feature of positively charged carbon because of the greater electronegativity of oxygen than carbon, and has been endowed with many classical reactions, such as the Barbier reaction, 52 Strecker reaction, 53 Schiff base reaction, 54 and so on. However, a stubborn problem is the aldehyde group is prone to autoxidize and produce peracid, which would reversely react with aldehyde by nucleophilic attack if sufficient oxygen was provided, that is, continuously exposed in air (Figure 1a).…”

Synthesis of α-exo-Methylene-γ-butyrolactones: Recent Developments and Applications in Natural Product Synthesis

“…However, when we revisited this methodology, we found that the transformation with 1 equiv, or a slight excess, of dimethyl zinc afforded the trans-configuration (as shown in XVI, scheme 23), and the use of an excess of dimethyl zinc simply promoted a further translactonization to give β-hydroxymethylα-exo-methylene-γ-butyrolactones (Scheme 23, 84). 48 However, this investigation revealed that syn-85 was unavailable from this palladium chemistry. This palladium catalyzed Barbier allylation/translactonization cascade reaction was exploited for the rapid construction of β, γ-disubstituted α-methylene-γbutyrolactones.…”

“…In particular, we analyzed sesquiterpene lactone syntheses from 2017. 67 To the best of our knowledge, there are 13 publications covering guaianolides (Maimone 2017, 68 Siegel 2017, 69 Hajra 2017, 70 Maimone 2019, 71 Metz 2021, 72 Usuki 2021 56 ), germacranolides (Corey 2018, 73 Arndt 2019 74 ), furanoheliangolides (Winssinger 2021), 9 1,10-seco-guaianolides (Winssinger 2021), 48 xanthanolides (Tang 2017), 75 a rearranged germacranolide (Lee 2021), 76 and sesquiterpene lactone scaffolds (Zografos 2021) (Figure 3). As shown in Figure 3, the representative are divided into different categories that are distinguished by colors for the different bond-breaking strategies.…”

“…27 Finally, the allylation/ tranlactonization can be achieved in one pot using palladium catalysis with ZnMe2 (see also Scheme 23). 48…”

“…Another application of Barbier-type allylation comes from our total synthesis of 1,10-seco-guaianolides. 48 Building upon our investigations of the Pd-catalyzed Barbiertype allylation, we harnessed an allylation/translactonization cascade in the total synthesis of various natural products. As shown in Scheme 27, treatment of aldehyde 74i with bromolactone 75 under palladium allylation conditions cleanly afforded the anticipated transesterified product 100.…”