New efficient protocol for aryne generation. Selective synthesis of differentially protected 1,4,5-naphthalenetriols

An Alternative Method for Generating Arynes from ortho-Silylaryl Triflates: Activation by Cesium Carbonate in the Presence of a Crown Ether

“…For example, we have recently succeeded in efficiently generating arynes from ortho-iodoaryl triflates bearing sensitive functional groups using a trimethylsilylmethyl Grignard reagent as an activator [30,31,33] instead of conventional activators such as n-butyllithium [35] or a turbo-Grignard reagent [36]. Herein, we report that cesium carbonate, in the presence of a crown ether, serves in place of a fluoride ion as an efficient activator for generating arynes from ortho-silylaryl triflates.…”

The First Anionic Thia‐Fries Rearrangements at Ferrocene: Ready Access to Trifluoromethylsulfonyl‐Substituted Hydroxyferrocenes and an Extremely High Interannular Stereoinduction between Cyclopentadienyl Ligands

“…After solvent removal 16 was obtained as a yellow solid; yield: 1.74 g (3.6 mmol, 85%); mp 145 8C (dec.). 1 meso-2,2'-Bis(trifluoromethylsulfonyl)-1,1'-ferrocenediyl Diacetate (18) At À78 8C a solution of LDA in THF [prepared from 1.6 M n-BuLi (5.8 mL, 9.2 mmol) in hexane and diisopropylamine (3 mL, 20.7 mmol) in THF (20 mL)] was added dropwise over 40 min to 1,1'-ferrocenediyl ditriflate (9, 2.03 g, 4.2 mmol) in THF (20 mL). The color changed from light yellow to deep red.…”

“…However, triflate elimination is a method which is now frequently used to facilitate aryne formation and which should be compatible with the presence of a tricarbonylchromium group. [17,18] Treatment of (phenyl trif-A C H T U N G T R E N N U N G late)tricarbonylchromium (2) with base, followed by hydrolytic work-up, did not, however, afford the desired (benzyne)tricarbonylchromium (1) or a trapping product thereof. Instead, in a rapid anionic thia-Fries rearrangement 2-(trifluoromethylsulfonyl)phenol complex 3 was formed in high yield (Scheme 1).…”

Synthetic study of ravidomycin, a hybrid natural product

“…Indeed, the C-glycoside formation of 11 went nicely to give 12 as a sole product (Scheme 3). Subsequent conversion including a benzyne-furan cycloaddition [4], introduction of the amino group and cyclization allowed the first total synthesis of ravidomycin. The final product was fully consistent with the natural product, except for the sign of [α] D value.…”