Intramolecular rearrangement of 1,3-bistriflate ester of thiacalix[4]arene to 1,2-counterpart: an efficient di-O-protection method for the stereoselective synthesis of anti-1,2-diethers

Reactions of thiacalix[4]arene 1,3-bistriflate: formation of thiacalix[2]phenoxathiins—structural and complexation studies

“…18 Hattori's group has also reported the formation of 2g produced by the intramolecular rearrangement of the precursor, 2a under several basic conditions. 2 Previously, we 10b and others 12a had reported similar intramolecular rearrangement of 1, the analogous 1,3-bistriflate of p-tert-butylcalix [4]arene under various Pd-catalysed reaction conditions.…”

“…As can be seen from entries 2 and 3, phenoxathiin 3 was also formed in the absence of added CuI as was found by Hattori and co-workers. 2 However, in general, higher yields of 3 were obtained when catalytic amounts (10 mol%) of Pd(II) were employed (entries 1, 3 and 5). When triethylamine was used as both the base and as the solvent, with Pd(II), 19 (entry 5) 3 was also formed, albeit in lower yield (28%) than when toluene and DBU were used.…”

“…2) via an indirect route, but more recently, Hattori and co-workers 1 reported a direct Ullmann-type conversion of 2 and also of 1, to the corresponding monobenzylamino thiacalix [4]arene derivatives 2c and 1c, respectively. They also reported that the 1,3-bistriflate of p-tert-butylthiacalix [4]arene 2 underwent intramolecular rearrangements under various reaction conditions (see below), and also formed a new macrocyclic compound, a bis(phenoxathiin) or ''thiacalix [2]phenoxathiin'' 3 (Fig. 3).…”

“…3). 1,2 Desroches, Parola and co-workers 3 were able to effect substitution of the narrow-rim hydroxyls of tetra-p-tertbutylthiacalix [4]arene itself via thermally-induced Newman-Kwart rearrangement reactions of the precursor tetra-O-thiacarbamoyl derivatives 4 and 4a, but these reactions led directly to the formation of the novel analogues of 3, namely, thiacalix [2]thianthrenes 5 and 5a, respectively (Fig. 3).…”

“…In connection with our own work, we were interested in extending our previous findings with the Sonogashira reaction 8,9 to the 1,3-bistriflate of thiacalix [4]arene (2), in order to study both the potential non-linear optical and also the complexation properties of suitably-designed narrow-rim arylethynyl derivatives of thiacalix [4]arene itself, such as 2e. Although we have thus far failed to synthesize 2e or other narrow-rim ethynyl derivatives using this approach, we herein report our recent findings 4 which complement in some instances those disclosed coincidentally in those recent publications of Hattori and co-workers 1,2 and also that of Desroches, Parola and co-workers 3 The same Sonogashira-type reaction conditions, (CuI, DBU and phenylacetylene in anhydrous degassed toluene) which we had successfully used with 1,3-bistriflate 1 to afford the corresponding 1,3-bis(phenylethynyl)calix [4]arene (1b) were therefore employed with p-tert-butylthiacalix [4]arene-1,3-bistriflate (2). However, with 2 these conditions afforded none of the desired corresponding phenylethynyl substituted product 2e.…”