Sesquiterpene alcohols with novel skeletons from the fungus (ascomycotina)

Synthesis and rearrangement of [1,1′-bicyclobutyl]-1-ols and spiro[3.4]octan-5-ols: a general access to bicyclo[3.3.0]octenes (hexahydropentalenes)

“…On the contrary, attempted additions of 13 to 1, and of 12a,b to 2-methyl-cyclobutanone (31) 22 failed. However, 10 6 reacted with 31 to give a single dimethylated [1,1 0 -bicyclobutyl]-1-ol, thought to be 32a, 23 and with 2,2-dimethylcyclobutanone (20) to give the trimethylated [1,1 0 -bicyclobutyl]-1-ol 33 (Scheme 5).…”

“…For the mechanism of the rearrangement of 37, we refer to a closely related example. 24 From a synthetic point of view it is interesting to note that 42, 45 and 46 represent partial structures of the linear triquinanes endo-hirsutene (47), 29 endo-capnellene (48) 30 and both ceratopicanol (49) 31 and cucumin-H (50), 27,32 respectively (Scheme 8). While examples for successful syntheses of angular triquinanes via cyclobutylmethyl to cyclopentyl rearrangements are known, 33 their potential for a synthesis of linear triquinanes remains to be explored.…”

NMR study of complex triquinanes and bulleranes derived from photoisomerization of aryl‐substituted norbornan‐2‐ones

“…A value of 11.0 Hz for 5 (10,11) is in accordance with a trans disposition of H-10 and H-11, as can be derived from the Karplus relationship.' Likewise, since the 5(7,8) and 5(7,9) coupling constants are negligible, the torsion angles 8 (7,8) and 8 (7,9) must be close to 90". This implies that H-3 and H-8 on the threemembered ring are /?-oriented.…”

“…A value of 6.8/7. conformation for 0 (7,8). Consequently, J(7,S) would be large (9-10 Hz), and the coupling constants for J(3,S) and J(3,4) would be ~m a l l e r .…”

“…The I3C NMR chemical shifts of 8 and of 12 and 13 are given in Tables 3 and 4, respectively. Unfortunately, it was not possible to obtain useful I3C NMR spectra for 9 and 10 owing to extensive decomposition during accumulation.…”