Studies on the Constituents of Aconitum Species. VII. On the Components of Aconitum Japonicum Thunb

TWOnew diterpenoid alkaloids, subcumine I and subcosine ( ? ) , were ~solated from the roots of Aconitum japonicum Thunb.The structures of these alkaloids were determined on the basis of spectral data, chemical evidence, and X-ray analysis.We also have isolated two known alkaloids, ezochasmaconitine ( 3 ) .and anisoezochasmaconitine (4).Recently, we reported an isolation of eighteen a l k a l o ~d s ~' ~ from Aconitum japonlcum Thunb.In thls paper w e report isolation and structure determination of two new Clg-diterpenoid alkaloids, named subcumine 11) and subcusine ( t ) together 4 with known alkaloids, ezochasmacon~tine ( ! 1 4 and anisoezochasmaconitine (4) .We also report the revised assignments of 13c-chemical shifts of C(9).C(10), and C(13l in the related Clg-diterpeno~d alkaloids.subcumine ( I ) , mp 200-202°C, CZ6HqlN07, was deduced a Clg-diterpenoid alkaloid from the molecular formula and the 'H-nmr spectrum which showed five methyl groups assignable to an N-CH2CE13, an acetyl, and three methoxyls, and two oxygenated methines at 6 4.02 (d, J= 7.9 Hz) and 4.76 It, J = 4.6 Hz, cl4p-H1 (See Experimental).This spectrum was similar to that of 14-acetylneoline4 (7, bul-.5 6 latine C , delstaphisagnine I with the exception of the signal at 6 4.02 ppm.The coupllng constant of the signal was slmilar to the value of C a-H in the nmr 6 7 8 spectra of blcoloridine (5, alkaloid A I and bicolorine 6-g-acetate9 (6) and the structure was assigned to 1. 1 3 ~-~m r and ir spectra of 1 also supported the structure.Finally, the structure of 1 was determ~ned by X-ray crystal analysis.-Perspective view of 1 was illustrated in Fig.1.-3; R. CO-C H 6 5 4; -R= CO-C6Hq-0CH3(p) Chart 1 '~-~rnr spectrum of subcusine (21, mp 194-196'C, C24H39N06, showed four methyl groups assignable to an N-CH2s3, three methoxyls, and two oxygenated methines at S 4.00 (d, J= 7.8 Hz, C6a-H) and 4.06 (t, J = 4.5 Hz, C14B-HI.The nmr spectrum of 2 suggested that the acetyl group was freefrom the structure of 1. Hydrolysis of 1 gave the compound 2, and the structure of subcusine (2) was determined to be -deacetylsubcumine.

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