Isolation, structure determination and synthesis of new dihydroisocoumarins from Ginkgo biloba L.

Dihydroisocoumarins from the Mangrove-Derived Fungus Penicillium citrinum

“…The absolute configuration of C-3 was also determined by circular dichroism (CD) spectroscopy (Figure 4). The negative circular dichroism at 259 nm (Figure 4) suggested the R configuration at C-3, by comparison with data for dihydroisocoumarins described in the literature [18]. Thus, compound 1 was named as penicimarin G, and the absolute configuration of 1 was defined as (3 R , 4′ R ).…”

“…The 1 H, 1 H-COSY, HMQC, and HMBC spectra allowed the complete assignment for 3 . Thus, compound 3 was named as penicimarin I, and the absolute configuration of C-3 was also determined to be R by CD spectra (Figure 4) [18]. …”

Anticancer Agents from the Australian Tropical Rainforest: Spiroacetals EBC‐23, 24, 25, 72, 73, 75 and 76

“…(S)-2-Tridecyloxirane (ent-24): [20] To a solution of (S)-1-chloro-pentadecan-2-ol (10.8 g, 41.3 mmol) in THF (55 mL) and MeOH (152 mL) was added a solution of sodium hydroxide (2.09 g, 52.2 mmol) in H 2 O (35 mL). The mixture was stirred at room temperature for 3 h. The THF and MeOH were then removed in vacuo and additional H 2 O (150 mL) was added.…”

“…To access the left-hand fragment 16 scalable amounts of enantiopure epoxide 24 were required. [18] Initially Jacobsen epoxide resolution methodology [19] was utilized, but this was later superseded by the method of Lepoittevin, [20] which provided 24 in large quantities and in high enantiomeric excess starting from (R)-epichlorohydrin (25) (Scheme 2). …”

“…Investigation into the convergence of the two halves (i.e., 29 and 36) concentrated on the use of dithiane (20) as the one carbon unit linker. Epoxide 29 was reacted with the anion of TBS-dithiane 37, which underwent the first addition step of the linchpin reaction followed by the Brook rearrangement.…”