The Structure and Synthesis of Tsitsikammafuran: A New Furanosesquiterpene from a South African Dysidea Sponge

Three furanosesquiterpenes, the new tsitsikammafuran (1) and the known nakafurans-8 (2) and -9 (3) were isolated from a South African Dysidea sponge. The structure of tsitsikammafuran, initially proposed as 3-[(furan-3-yl)methyl]-p-cymene, from a combination of biosynthetic arguments and the available spectroscopic data, was unequivocally confirmed by the synthesis of 1 from thymol. The synthesis of two regioisomers of tsitsikammafuran, 4-[(furan-3-yl)methyl]-m-cymene (4) and 2-[(furan-3-yl)methyl]-p-cymene (22), from p-cresol and 2-bromo-2-nitrocamphane respectively, further supported the structural assignment of 1.