Efficient Asymmetric Synthesis of the C₉−C₂₁ Portion of the Aplysiatoxin and Oscillatoxin Marine Natural Products

The Cyanobacterial Origin of Potent Anticancer Agents Originally Isolated from Sea Hares

“…(9)). Their biological activities have prompted numerous synthetic studies [71,72]. It is interesting to note at this point that aplysiatoxin (43) is the para-isomer of manauealide B (46) reported from a red alga [73] (Fig.…”

Gold(I)‐Catalysed Cycloisomerisation of 1,6‐Cyclopropene‐enes

“…Cyclopropenylcarbinol 12 , bearing a benzyl ether at a remote position, was easily synthesised from 4‐benzyloxybutanal ( 11 ,35 42 %; Scheme ). When aldehyde 13 , derived from the ( S )‐Roche ester, was used as the electrophile,36 a mixture of epimeric cyclopropenylcarbinols 14 and 15 was obtained in a 30:70 ratio (83 % overall yield; Scheme ), which were separated by MPLC (MPLC=medium pressure liquid chromatography). To assign their relative configuration, an equimolar mixture of epimeric alcohols 14 and 15 was subjected to Sharpless kinetic resolution in the presence of (+)‐DET, which showed that the major epimer 15 was selectively oxidised to enal 16 under those conditions (Scheme ) 37.…”

Preparation of Alkyl Ethers with Diallyltriazinedione‐Type Alkylating Agents (ATTACKs‐R) Under Acid Catalysis

“…Methyl (2 R )‐3‐[(4‐Methoxybenzyl)oxy]‐2‐methylpropionate (7c‐PMB): , Following GP‐2 with slight modification, 3 (2.0 mg, 5.9 µmol) in 1,4‐dioxane (0.4 mL) was added to a mixture of 6c (33.1 µL, 0.300 mmol), ATTACK‐PMB (122.1 mg, 0.37 mmol), and molecular sieves 5 Å (37.5 mg) in 1,4‐dioxane (1.1 mL) at room temperature. After 10 min, the reaction mixture was diluted with Et 2 O (6 mL) and filtered.…”