
%0 Journal Article
%A Russell, CA 
%A Sutherland, MD 
%T Terpenoid chemistry. XXV. The absolute configuration of (&#8211;)-ngaione, (&#8211;)-epingaione and related substances
%J Australian Journal of Chemistry
%D 1982/09/01
%V 35
%N 9
%P 1881-1894
%K 
%R https://doi.org/10.1071/CH9821881
%U https://www.publish.csiro.au/paper/CH9821881 
%X The absolute configuration of (-)-ngaione has been confirmed as (2'S,5'R)-4-methyl-1-(5'-methyl-2',3',4',5'-tetrahydro[2',3''-bifuran]-5'-yl)pentan-2-one as was proposed by Hegarty, Kelly, Park and Sutherland in 1970, by converting it into (&#8211;)-ngaiane, (2S,5S)-5-methyl-5-(4''-methylpentyl)-2,3,4,5-tetrahydro[2,3'-bifuran], which is shown to resist ring opening by nucleophiles. Further confirmation was obtained by the ozonolysis of (&#8211;)-ngaiane to (&#8211;)-(4R)-4,8-dimethylnonan-4-olide comparable in molecular rotation with (&#8211;)-(4S)-4-methylhexan-4-olide which has been correlated with (&#8211;)-(R)-linalool. Wolff-Kishner reduction of the hydrazone or semicarbazone of (&#8211;)-ngaione yields mainly an E,Z(1S,4&#958;)-1-(furan-3'-yl)-4,8-dimethylnon-5-en-1-ol with some ngaiane. Being (+)-ngaione, ipomeamarone does not have the absolute configuration assigned by Kubota, Nakajima and Matsuura in 1964. The name ipomeamarone is redundant, implies an incorrect stereochemistry and should be abandoned. 
