Synthetic Studies Toward Pectenotoxin 2. Part II. Synthesis of the CDE and CDEF Ring Systems

Abstract

A convergent synthesis of the CDE and CDEF ring systems of pectenotoxin-2 from C and F ring precursors is described.

Studies towards asymmetric synthesis of 4(S)-11-dihydroxydocosahexaenoic acid (diHDHA) featuring cross-coupling of chiral stannane under mild conditions

“…Firstly, the iodine-promoted iodolactonization was utilized; the eicosapentaenoic acid was successfully transformed into iodolactone (11) in 62% yield. Firstly, the iodine-promoted iodolactonization was utilized; the eicosapentaenoic acid was successfully transformed into iodolactone (11) in 62% yield.…”

“…The epoxide (13) was hydrolyzed to triol by treatment with aqueous perchloric acid; periodate scission of the vicinal diol was employed again. [11][12][13] Subsequently, the synthesis of chiral α-hydroxy α-stannane (8) using asymmetric stannylation of the aldehyde (9) by utilizing the wellestablished protocol with tributyltin hydride/diethyl zinc followed by one-pot protection was realized in 60% isolated yield. Based on our wellestablished protocol, the stannylation reaction of the aldehyde (4) with tributyltin hydride/diethyl zinc followed by one-pot protection was utilized, the chiral α-hydroxy α-stannane (3) 10 was obtained in 27% yield from the epoxide 13.…”

“…The chiral α-hydroxy α-stannane (3) was synthesized by the route shown in Scheme 2. Firstly, the iodine-promoted iodolactonization was utilized; eicosapentaenoic acid was successfully transformed into iodolactone (11) in 62% yield. This compound was immediately used for the next step as it may decompose when exposed to light.…”

“…The 4-oxobutyl acetate ( 9) is generated via oxidative cleavage of 4-pentenyl acetate (10) with ozone in 76% yield. [11][12][13] Subsequently, the synthesis of chiral α-hydroxy α-stannane (8) using asymmetric stannylation of the aldehyde (9) by utilizing the well-established protocol with tributyltin hydride/diethyl zinc followed by one-pot protection was realized in 60% isolated yield. 6 Notably, the chiral ligand (II) is the most suitable one for this particular catalytic stannylation through ligands optimization.…”

Enantioselective Total Synthesis of (−)-Alstoscholarisine A

“…In spite of no precedent, we were audacious to propose that tricycle 8 could be generated via an asymmetric intramolecular Friedel–Crafts alkylation of indole 9 with a secondary allylic alcohol by taking advantage of Carreira’s iridium catalysis system . The requisite Friedel–Crafts alkylation substrate 9 could be prepared directly from two simple starting materials, 3-methylindole ( 10 ) and 4-vinylbutyrolactone ( 11 ) …”