A selective method for oxygen deprotection in bistrimethylsilylated terminal alkynols

Abstract

A selective method for oxygen deprotection of bistrimethylsilylated -alkynols is described using sulfonic acid type exchange resins in ether solvent. The method offers the advantages of selectivity toward the silicon-oxygen bond, easier monitoring of the reaction and workup, and higher yields (>75%). Comparisons are made between standard aqueous acid procedures and a series of resins.

Cyclization of acetylenic alkyllithiums

“…3 ), 0.98 (t, J = 7.36 Hz, 3 ), 1.26-1.52 (m, 8 ), 1.82-2.08 (m, 2 ), 2.13-2.30 (overlapping patterns [2.16 (t, J = 6.78 Hz, 3 ), 3.21 (td,/, = 6.94 Hz, , = 1. 43 Hz, 2 H)]); l3CNMR (CDC13) 6.92,11.74, 13.58,18.37,21.87,28.48, 31.27, 31.45, 32.53,35.77,81.98,82.47; mass spectroscopic molecular weight caled for C|2H2iI 292.0688, found 292.0678.…”

“…Chem. 5-(trimethylsilyl)-4-pentyn-1 -ol43), trimethyl(6-iodo-1 -hexynyl)silane ( 10)16 (via the mesylate from 6-(trimethylsilyl)-5-hexyn-1 -ol44), 1 -iodo-5-decyne (6),361 -iodo-4-nonyne,36 and 11 -iodo-5-undecyne (43).36 The structures of the remaining iodides were established on the basis of the following spectroscopic data.…”

Incorporation of a Tethered Alcohol Enables Efficient Mechanically Triggered Release in Aprotic Environments

“…Polymers were synthesized via controlled radical polymerization using Cu wire/Me 6 TREN in dimethyl sulfoxide from the corresponding Diels–Alder initiators bearing α-bromoester functional groups. , Bis-initiator (±)- 8 with a tethered primary alcohol was initially employed in the synthesis of PMA-OH ; however, some undesired release of the hydroxycoumarin cargo occurred during polymerization in the presence of the Me 6 TREN ligand, likely through activation of the alcohol toward intramolecular carbonate substitution. Instead, polymerization from TBS-protected bis-initiator (±)- 7 followed by removal of the TBS protecting group using an ion-exchange resin (Amberlyst 15) afforded PMA-OH with M n = 86 kDa and Đ = 1.10 (Figures S8 and S9, see the SI for details). A similar polymerization procedure was used to prepare PMA-Me ( M n = 92 kDa, Đ = 1.10), allowing for the direct comparison of mechanochemical behavior and the influence of the tethered alcohol as well as PMA-Control ( M n = 87 kDa, Đ = 1.16) to confirm the mechanical origin of reactivity …”