Structures of spiramines E (1), F (2) and G (3) were elucidated by chemical and spectroscopic means. In the previous paper, we reported the isolation and structures of four new atisine type alkaloids, spiramines A-D, from the roots of Spiraea japonica var. acuminata which has been used as a folk medicine in China. In the course of the investigation on the constituents of the plant, we isolated three new atisine type alkaloids; spiramines E (1), F (2), and G (3). Here we report a full account on the structures of these alkaloids. The formula for spiramine E (1), amorphous, [α]₀ - 97 (CHCl₃), was determined as C₂₆H₃₇NO₅ on the basis of high resolution mass spectrum and elemental analysis. An atisine type skeleton for spiramine E was deduced by comparing its ¹³C-nmr shift values with literature data of spiramines A - D. Other spectroscopic analysis showed the presence of an exo-methylene group [δ 5.28, 5.03 (each 1H, t, J = 1.5 Hz, 2H-17); ν 1650 cm⁻¹], a secondary acetoxy group [δ 1.68 (3H, s), 5.46 (1H, br s); ν 1710, 1240 cm⁻¹], and a primary acetoxy group [δ 1.75 (3H, s), 4.16 (2H, t, J = 6 Hz, 2H-22)]. The presence of an ether linkage between C-7 and C-20 in spiramine E (1) was presumed by the signals of ¹H-nmr [δ 4.53 (1H, br s, H-20), 3.60 (1H, d, J = 5 Hz, H-7β)], which were the same as those of spiramine A (4). On irradiation at δ 5.46, both of the signals at δ 5.28 and 5.03 were changed to doublets with J = 1.5 Hz, demonstrating the location of the secondary acetoxy group on C-15, and the α-configuration of the 15-acetoxy group was presumed from the ¹³C-nmr shifts values of C-7 and C-15 in spiramine E (1) which were very close to those of spiramine A (4). Spectral data (Table 1) for spiramine F (2), amorphous, [α]₀ -101° (CHCl₃), C₂₄H₃₅NO₄, indicated that this compound was the deacetyl spiramine E. In fact, acetylation of spiramine F (2) afforded spiramine E (1). In order to confirm the deduced structures for spiramines E and F, spiramine F (2) was treated with sodium borohydride to give triol (6), which had already been obtained from spiramine A (4) in the same way. The existence of an ether linkage between C-7 and C-20 in spiramines E and F was chemically proved by the following oxidative cyclization using triol (6). Oxidation of triol (6) with K₃Fe(CN)₆ gave deacetylspiramine F (5) which was identical with the product obtained by the hydrolysis of spiramine F (2). It was interesting that an ether linkage between C-7 and C-20 was formed from triol (6) while an oxazolidine ring was formed from dihydroajaconine (7). The difference of the two compounds is just the configuration of 15-hydroxy group. Spectroscopic analysis of spiramine G (3), needles, mp 160-162 °C, [α]₀ -16° (CHCl₃), C₂₂H₃₁NO₃, indicated the presence of an exo-methylene group [δ 4.92, 4.74 (each 1H, m), ν 1650 cm⁻¹], a primary hydroxy group [δ 3.60 (2H, m, 2H-22); ¹³C-nmr, δ 60.3 (t)], a secondary hydroxy group [δ 3.20 (1H, ddd, J = 6, 8, 11 Hz), ¹³C-nmr, δ 76.2 (t)], and a carbonyl group [ν 1700 cm⁻¹; ¹³C-nmr, δ 219.8 (s)]. The secondary hydroxy group was assigned to be of 7-α configuration by its chemical shift and the coupling constant value of ¹H-nmr which were similar to those of triol (6). The location of the carbonyl group was deduced as follows: the NOE experiment between the signals of δ 4.92 (17-H) and δ 2.70 indicated the latter should be H-12. Irradiated at δ 2.70, the signal at δ 2.31 (1H, dt, J = 3, 20 Hz, 13β-H) changed to a doublet of doublet (J = 3, 20 Hz, long range coupling with H-11) and the signal at δ 2.19 (1H, dd, J = 3, 20 Hz, 13α-H) changed to a doublet (J = 20 Hz). This shows that there is no proton at C-14. A close inspection of ¹³C-nmr spectra of spiramine G (3) and triol (6) revealed that the quaternary carbon signal at δ 51.8 in spiramine G (3) was shifted to the down field about 10 ppm, which indicated that the carbonyl group was located at C-14. Three-dimensional single-crystal X-ray analysis provided the total structure for spiramine G (3). Spiramine G (3) is the first C-20 diterpene alkaloid containing the carbonyl group at C-14.