NH₄HF₂as A Selective TBS-removal Reagent For The Synthesis Of Highly Functionalized Spiroketal Via Tandem Deprotection/Spiroketalization Procedure

NH4HF2has been used for the first time to selectively remove the TBS protecting groups from diol ketone precursors in the synthesis of highly functionalized spiroketals. This method allows the synthesis of [5,6],[6,6], and [6,7] spiroketal skeletons, as well as benzannulated spiroketal with retention of acid-sensitive groups. In this way, spiroketals can be synthesized with diverse substituent groups in the skeleton or on side chains. To demonstrate the utility of this methodology, the diverse transformations of highly functionalized spiroketal2-19f were also investigated.