Heartwood constituents of Swartzia madagascariensis

Photocyclisations of some 3‐alkoxy‐2‐thienylchromones

“…To elucidate the stereochemistry of 5a-5c, 7a and 7c, the correlation between dihedral angle ( ) and coupling constant (J) was invoked. The vicinal coupling ( 3 J) between H-3a and H-11b was found to be 8.1 Hz that reflects the cis fusion of ring C and D. Such a notion is in concurrence with the naturally occurring pterocarpans [31][32][33][34][35][36][37] and our earlier results [17][18][19][20][21][22][23][24][25]. The interrelationship between H-4 and H-3a in these products ( 3 J = 10Hz) indicates them to be cis, which is not without precedent [38].…”

Photochemical Transformations of Some 2-(5-Methylthiophen-2-yl)-3-[(naphthalen-2-yl)methoxy]-4H-chromen-4-ones Involving Type-II Process

“…Here, the interesting feature in the photoproduct isolated is the stereochemistry of ring C, which is in ψ-chair conformation (Figure 1). The vicinal coupling constant ( 3 J) between H-3a and H-11b was found to be 10.0 Hz in 3d, which reflects the cis-fusion of ring C and D as in accordance with the naturally occurring pterocarpans, [19][20][21][22] which possess a close similarity with the photoproducts under consideration as well as concerning the relative stereochemical disposition of H-3a and H-4. The 3 J＝7.8 Hz adequately indicates them to be cis, thus placing the bulkier naphthyl group in ψ-equatorial conformation.…”

Metabolites of Medicarpin and Their Distributions in Rats

“…Pterocarpans are the second largest group of dihydroisoflavonoids and have a special structure skeleton (benzopyran-benzofuran four-ring system). They were originally isolated from plants [1] and then regarded as an important group of phytoalexins, which have antifungal [2] and antibacterial [3] effects. In recent years, many new bioactivities of pterocarpans have been discovered, such as anti-inflammation [4,5,6], antitumor activity [7,8,9], anti-osteoporosis [10,11,12], antimalarial [13], antioxidant [14,15,16], inhibition of neuraminidase [17,18,19] and melanin synthesis [20], estrogenic and anti-estrogenic activity [21], anti-clastogensis [22], immunosuppressive activity [23], and inhibition of acetylcholinesterase [24].…”