Synthesis of the C(1)−C(25) Fragment of Amphidinol 3:  Application of the Double-Allylboration Reaction for Synthesis of 1,5-Diols

Abstract

[structure: see text] A synthesis of the C(1)-C(25) fragment of amphidinol 3 is described. The synthesis features two applications of double allylboration reaction methodology for the highly stereoselective synthesis of 1,5-diol units in the C(1)-C(15) segment.

Transition metals in organic synthesis: Highlights for the year 2005

“…Intramolecular couplings were used in synthesis of isocomplestatin [244] and biphenomycin B [245]. (11) Alkyl boron reagents were used in synthesis of for example minfiensine [246], zoapatanol [247], dibenzocyclooctadiene lignans [248,249], the C1-C25 fragment of amphidinol 3 [250], (+)-SCH-351448 [251], the C10-C24 fragment of inostamycins [252], (+)-brefeldin C [253], (+)-wortmannin [254], cordiaquinone J and K [255] and cannabinoid antagonists [256].…”

“…Copper mediated an intramolecular coupling of two aryl bromides in a synthesis of dibenzocyclooctadiene lignans (Eq. (26)) [249,250].…”

“…Noyori's ruthenium catalyst was used to reduce an imine in a synthesis of (+)-laudanosine and (−)-xylopine [327]. A Noyori-type reduction of a cis-alkene in the presence of trans-alkenes was used in a synthesis of C1-C25 fragment of amphidinol 3 [250].…”

Enantio- and Diastereoselective Synthesis of N-Acetyl Dihydrotetrafibricin Methyl Ester

“…We initially envisioned that 1 would be accessed by a late stage, fragment assembly double allylboration reaction of aldehydes 4 8a and 2 8c,d with the first generation reagent 3 . 9 As it turns out, several attempts 8b at this coupling with these and related intermediates proceeded in low yield, which we ultimately traced to the instability of 4 . Curran’s group reported similar issues in their attempts to effect a Kociensky-Julia olefination reaction with an analog of 4 .…”

“…5c These observation prompted us to reexamine our synthesis and to plan to install the polyene unit at the late stage from the Horner-Wadsworth-Emmons reaction between the known phosphonate 5 8a and the C(9)-C(40) aldehyde 6 . We envisaged that 6 could be obtained in a highly convergent way from a ( E )-1,5- anti double allylboration reaction 9 of aldehydes 2 and 7 with 1,3-bifunctional allylborane 3 . Key aldehyde intermediate 2 would be accessed by applying an ( E )-1,5- syn double allylboration reaction of aldehydes 8 and 10 and the 1,3-bifunctional allylborane 9 .…”