A Highly Congested Dioxapyrenophane from an Attempted Synthesis of the Highly‐Strained 1,1,6,6‐Tetramethyl[6](2,11)teropyrenophane

Abstract

AbstractSynthetic studies aimed at the synthesis of 1,1,6,6‐tetramethyl[6](2,11)teropyrenophane (3 a) led to the synthesis of the structurally unusual dioxa[6.3.3](7,1,3)pyrenophane 29. The strategic approach to access 3 a resembled the one that was successfully applied in the synthesis of the higher homologues 3 b‐e, but had a key difference: three‐atom bridges were utilized instead of two‐atom bridges in the construction of the intermediate pyrenophanes which were slated to serve as precursors to access 3 a. After stepwise approaches to construct the bridges failed, it was found that two ether bridges could be installed easily in the same reaction to afford dioxa[6.3.3](7,1,3)pyrenophane 29. Considerable steric congestion around the dioxa[3.3]metacyclophane substructure arises from the presence of a methyl group on each of the benzylic positions of the three‐atom bridges. Although the conversion of 29 into a [6](2,11)teropyrenophane was unsuccessful, the finding that ether bridges in this structurally uncommon dioxacyclophane could be formed easily offers new opportunities for the synthesis of related cyclophanes that may ultimately serve as viable precursors for the synthesis of [n](2,11)teropyrenophanes.