Asymmetric Synthesis of (+)- and (−)-Pauciflorol F: Confirmation of Absolute Stereochemistry

Abstract

An efficient, formal enantioselective synthesis of (+)- and (-)-pauciflorol F has been achieved using a recently introduced oxazolidinone controlled torquoselective Nazarov reaction. The absolute stereochemistry of pauciflorol F and its biosynthetic precursors has been unambiguously confirmed using X-ray crystallography.

Trans‐Selective Radical Silylzincation of Ynamides

“…[23,25] The prepared b-bromoenamides participated readily in Suzuki-Miyaura-type cross couplings. Reaction of Z-26 with 4-anisylboronic acid afforded a-carbonyl b-substituted enamide Z-27 [23,26] in 73 % isolated yield in spite of a partial isomerization during the coupling reaction. Z-29 was prepared similarly from Z-28 and phenylboronic acid in 50 % yield, and no isomerization was observed.…”

Sulfoxide‐Based Enantioselective Nazarov Cyclization: Divergent Syntheses of (+)‐Isopaucifloral F, (+)‐Quadrangularin A, and (+)‐Pallidol

“…Another elegant approach is the Nazarov cyclization . Flynn and coworkers, implemented Evans oxazolidinones to control the Nazarov cyclization, which resulted in an enantioselective synthesis of 1 with notable success . However, the multiple steps towards the enone substrates and removal of the auxiliary may deteriorate the overall efficiency.…”

“…The assignment of the absolute configurations of the diastereomers 11 a–z was based on the X‐ray crystal structure analysis of 11 a (see the Supporting Information) . Moreover, the absolute configuration of 12 a–z could be confirmed to be S by comparison with the known data and the X‐ray crystallographic analysis of 12 a (see the Supporting Information). A possible reaction mechanism was described using 10 a as an example (Scheme ).…”

Palladium/Norbornene‐Catalyzed Indenone Synthesis from Simple Aryl Iodides: Concise Syntheses of Pauciflorol F and Acredinone A

“…[15] Several elegant routes for its synthesis have been developed to date. [2,16] Our approach started with at wo-step preparation of mixed anhydride 10 from commercially available aldehyde 8. [17] As expected, the subsequent Pd/N1catalyzed annulation between anhydride 10 and aryl iodide 3t provided indenone 11 in 82 %y ield, whose structure was confirmed by X-ray crystallography.…”