Struktur und Partialsynthese von dimerem Coleon F

Structure and Partial Synthesis of Dimeric Coleon F Coleon F ( 1a ), on standing in solution, slowly dimerizes to the labile C(7)‐epimeric spiro‐dihydrofuranes 2a/2b whose structures were elucidated by spectroscopic methods. Oxydative addition of 1a to another molecule of 1a in the presence of Fétizon 's reagent rapidly yields 2a/2b , thus confirming their structures as (4b S ,9 RS ,10′a S )4,4a,10′,10′a‐tetrahydro‐1′,6‐dihydroxy‐1,2,4a,7′,8′,10′a‐hexamethyl‐3′,7‐bis(2‐propenyl)‐spiro[3 H ,9 H ‐phenanthren‐9,5′‐5′ H ‐phenanthro[1,10‐ bc ]furan]‐2,3,5,8,9′‐pentone.