Stereoelectronically‐programmed molecular ‘lego’ sets

The observation that the syn‐isomer 1 of 1,4:5,8‐diepoxy‐1,4,5,8‐tetrahydroanthracene becomes involved in a series of highly diastereoselective Diels‐Alder reactions with 2,3,5,6‐tetramethylene‐7‐oxabicyclo[2.2.1]heptane 2 to form, in excellent overall yield, the novel macropolycyclic compound 6 ‐ a potential precursor of [12]beltene 7, [12]collarene 8, [12]cyclacene 9, and the perhydro[12]cyclacene derivative 10 ‐ is interpreted in terms of the stereoelectronic characteristics of the dienophilic components of 1 and the diene components of 2, and obvious steric factors, combining to favour one particular stereochemistry out of eight possibilities for the transition states involving each of the four different cycloaddition steps.