Absolute configuration of homoisoflavanones from species

Structure and absolute configuration of (–)-(3R)-5,7-dimethoxy-3,9-dihydro-4'-eucomnalinyl p-bromobenzoate: an uncommon case

“…The full agreement between observed z~ ° and calculated AW, which holds even for the Friedel pairs not included in Table 3, gives convincing evidence of the correctness of the 01 4"" "~3 4 -4 9 14"2 10.6 (7) 9"2 -6 5 -6 16"3 -7"4 (8) -6"8 2 -1 6 8"9 9.7 (4) 9"9 -1 4 6 13.9 4"3 (8) 3"9 -2 -1 -5 9"6 -9.7 (4) -12"9 2 0 5 8"5 6"4 (4) 6"2 -3 0 -5 10.2 9'0 (8) 8"5 -'2 -3 4 10.3 -7"2 (6) -7'1 2 2 -4 9"2 ll.l (4) 9"3 2 0 -4 8.4 4.8 (6) 6"9 1 -1 -4 7"3 -13"8 (4) -14.7 2 -3 -4 10"7 -4.3 (7) -7"2 0 4 3 10.6 -9.4 (8) -12.2 -1 -3 -3 9.5 -14.9 (6) -13.1 2 -6 3 11.2 4.7 (6) 9.9 3 3 -2 11.8 6.3 (4) 5.2 -2 0 2 6-4 -5.7 (3) -4.7 2 -4 -2 10.1 10"7 (6) 10.9 1 -3 1 6-8 18"5 (4) 17"0 4 5 -1 17"2 5"1 (11) 4-8 assumed R chirality at C(3). This result, moreover, agrees with that obtained by the chiral exciton coupling method (Adinolfi et al, 1988).…”

Sappanin-type homoisoflavonoids from Sansevieria trifasciata Prain

“…The absolute configuration of compound 1 was determined on the basis of its small negative specific rotation values (À12.3) which is typical feature for (3R) (Amschler et al, 1996Zhou et al, 2013. Furthermore, a negative Cotton effect observed in the 287-295 nm region (292 nm (De = À1.01)) of the electronic circular dichroism (ECD) curves of compound 1 is indicative of the 3R configuration (Adinolfi et al, 1988). Consequently, the structure was elucidated as (3R)-7-hydroxy-8-methoxy-3 0 ,4 0 -methylenedioxyhomoisoflavanone, a new sappanin-type homoisoflavonoid to which we gave the trivial name trifasciatine A.…”

Taste‐Active Compounds in a Traditional Italian Food: ‘Lampascioni’

“…Compound 2 displayed a singlet signal at d 3.94 ppm, a chelated OH signal at 12.28 ppm, and a single aromatic H-atom signal at 6.15 ppm. The exact position of the MeO group has been confirmed by a NOE experiment between the MeO group and the H-atom HÀC (6). Compound 3 displayed a similar pattern in the NMR spectrum, but the singlet H-atom at d 6.05 ppm did not show a NOE correlation upon irradiation of the MeO group, so that it must be situated at C (8).…”

“…Compound 4 obtained according to the Scheme was chromatographically and spectroscopically identical to that obtained from the natural derivative 3, therefore, confirming its structure. The structure of compound 2 was confirmed by converting it to its trimethyl derivative 13, the structure of which had been described in [6].…”