A highly stereoselective route to medium-ring-sized trans-alkenolides via oxidative fragmentation of bicyclic oxycyclopropane precursors: application to the synthesis of (+)-recifeiolide

First Synthesis and Characterization of Stereoisomers of Choleretic Drug Dihydroxydibutylether

“…[26,27] Protection of the hydroxyl group with TMSCl gave the key intermediate 9a, whose spectral data and optical rotation were consistent with those reported. [23,28] Then using Olah's method, [29] 4a and 9a were treated with trimethylsilyl triflate and triethylsilane in dry CH 2 Cl 2 at 0 ℃. The stirring was continued at 0 ℃ for 10 min, then at room temperature for 5 h to give 10a (39%) along with 11 in 12% yield.…”

Generation of Mixed Anhydrides via Oxidative Fragmentation of Tertiary Cyclopropanols with Phenyliodine(III) Dicarboxylates

“…Preparation of cyclopropanols 1g and 1h is described in the Supplementary Materials . Peptide cyclopropanol 1e and bicyclic cyclopropanols 1f and 1i have been prepared by following the published protocols [ 30 , 39 ]. Silica gel 40–100 μm was used for column chromatography; silica gel 60F 254 plates were used for TLC.…”

“…In 2014, we noticed that oxidation of cyclopropanols with PIFA in CH 2 Cl 2 affords mixed anhydrides of trifluoroacetic acid (TFA) as by-products [ 30 ], a plausible result of nucleophilic attack of TFA on the carbonyl group of A ( Scheme 1 ), which occurs in the absence of large excess of a competitive nucleophile. Generation of mixed anhydride as intermediate in the oxidation reaction with PIDA in acetic acid was also evidenced by Momose and co-workers in 1995 [ 25 ].…”

Copper(I)‐Catalyzed Chemoselective Coupling of Cyclopropanols with Diazoesters: Ring‐Opening C−C Bond Formations

“…In connection to our interests in both carbene chemistry and cyclopropanes, [5] we have chosen to explore cyclopropanols as carbon nucleophiles in transition-metalcatalyzed carbene-transfer reactions,considering the fact that ring-strain relief should provide an additional driving force for the transformation. [6] While cyclopropanols have been previously employed as carbon nucleophiles in reactions with protonic acids, [7] hypervalent halogen compounds, [8] or metal salts, [9] an obvious reaction between cyclopropanols and diazo compounds is nevertheless the metal-catalyzed O À Hi nsertion with the carbene generated (Scheme 1d). [10] To address this unmet challenge,herein we describe our development of ac opper(I)-catalyzed coupling between cyclopropanols and diazo compounds (Scheme 1e).…”