Utahin, a ditropolonofuran

Synthesis and characterization of bistropolonato oxovanadium(IV and V) complexes

“…The crystal and molecular structure of tropolone [15] and some of its derivatives [16,17] as well as those of the bis(tropolonato) complexes of Cu(II) [18] and Zn(II) [19] are known.…”

The X-ray crystal structure and absolute configuration of maytenol, a reduction product of the bis-diterpene maytenone

“…6 177(6) 3 367(5) 8 lOO (10) 2 890( 6) 934) 7 982 (9) 2 681( 5) 870( 4) 6 620(8) 3 592(5) 3 447(4) 8 256(8) 2 839(4) 2 449(4) 6 966(6) 4 889(4) 2 7934) 5 817( 8) 3 704( 5) 2 216(4) 4 809( 8) 5 379( 6) 2 870(5) 7 490 ( 10) 1 839( 6) 946( 5) 9 728 (6) 4 560(3) 2 406(3) 10 587( 6) 3 932(3) 2 671(3) 9 949( 4) 5 857( 2) 1753(2) 11 162 (7) 3 563( 4) 2 161(3) 10 650 (5) 5 006(3) 7 13(2) 10 531 (6) 5 148( 4) 1994(3) 10 802 (7) 3 822( 4) 1423(3) 11 525 (6) 3 022(4) 3 534(3) 10 901 (6) 3 845(4) 3 456(3) 9 804 (6) 3 854(4) 3 918(3) 12 763 (8) 5 754( 5) 1375( 4) 11 669 (7) 4 582(4) 3 641(4) 12 459 (7) 4 864( 4) 1364( 4) 12 126 (7) 2 956(4) 2 268(3) 11 801 (6) 2 752(4) 4 301(3) 10 112 (7) 3 665(5) 4 687(3) 12 555 (6) 2 946(4) 3 028(3) 12 097(8) 1 849(4) 4 291( 4)…”

“…It follows that maytenone should now be represented by the stereostructure (9), and several important features regarding the biosynthesis of maytenone can now be discussed. First, oxidation of the precursor ferruginol ( 6) must occur at the less hindered a face to give the hydroxycyclohexadienone (10). Diels-Alder dimerisation of ( 10) then proceeds with union of the two a faces of the monomers according to the normal endo rule to give mayte- A, must reflect the added internal strain due to the additional alicyclic rings substituent upon the central nucleus.…”

A fresh look at natural tropolonoids

“…The only structure of this type is utahin 33, a ditropolonofuran isolated from the tree Juniperus utahensis. 50 Note, however, that chaetospiron 32 is also a ditropolonoid material.…”