Abstract The reaction of octahydroxycyclobutane (2) with activated triethylborane gives a low yield of the thermochromic 2, 6-diethyl-1, 3, 5, 7-tetraoxa-2, 6-dibora-4, 8-octalindione (5b) by ring cleavage of 2. Additional examples of this novel class of compounds have also been prepared directly by reacting dihydroxyfumaric acid (6) with various alkyl-or arylboranes. With the exception of the tert-butyl-(5f) and the aryl derivatives 51, m, the new compounds ...