A Direct Synthesis of O-Methyl Claussequinone
The reaction of a chromene with BH3 followed by treatment with benzoquinone and air is the key step in a direct entry to O-methyl claussequinone.
Reprinted (adapted) with permission from The Journal of Organic Chemistry; 68(11); 4517-4518. Doi: 10.1021/jo030026j. Copyright 2003 American Chemical Society.