Construction of Two Vicinal Quaternary Carbons by Asymmetric Allylic Alkylation: Total Synthesis of Hyperolactone C and (−)‐Biyouyanagin A

Abstract

In this Communication, the discussion of work by the Kraus research group was not precisely expressed and should be corrected to the following: Kraus and Wei [3d] reported that 7 and its diastereomer, which were claimed to be isolated as by-products in their elegant synthesis of racemic hyperolactone C, could not be converted into a lactone using heat, acid (PTSA), or base (tBuOK, NaH, or KH) catalysis. However, careful analysis and comparison of the NMR data of 13 (1:1 mixture of diastereomers) with both the by-products reported by Kraus and Wei indicated that they were identical (see the Supporting Information). Moreover, the value of d = 155.9 ppm in the 13 C NMR data listed for compound 13 in the Supporting Information should be removed. The authors are grateful to Prof. David Hodgson of Oxford University for pointing this out.

Catalytic enantioselective synthesis of quaternary carbon stereocentres

“…8b). 70 Other significant recent developments in this area include the use of a vinyl epoxide as a coupling partner in the total syntheses of (−)-biyouyanagin A and hyperolactone C, 71 and the application of molybdenum 72 and iridium 73 catalysts in enantioselective allylic alkylation reactions. In addition, the enantioselective C-3 allylation of an indole derivative using allyl alcohol in combination with a trialkylborane as the alkylating reagent was featured in a synthesis of (−)-esermethole.…”

ChemInform Abstract: Construction of Vicinal Quaternary Stereogenic Centers by Enantioselective Direct Mannich‐Type Reaction Using a Chiral Bis(guanidino)iminophosphorane Catalyst.

“…Further investigation of the substrate scope was performed by changing the aryl substituent of 3 (entries [6][7][8][9]. As ignificant decrease in reactivity was observed when 2f,bearing acyclohexylmethyl group was used, thus affording the desired product 4ff in moderate yield even at an elevated temperature (À20 8 8C; entry 5).…”

“…Whereas use of the less basic guanidine-derived TBD and P1-tBu phosphazene (entries 3a nd 4) resulted in the formation of 4aain only atrace amount, the use of P2-tBu phosphazene,t he basicity of which is stronger than those of TBD and P1-tBu phosphazene,d ramatically accelerated the reaction, thus affording 4aa in good yield (entry 5). To improve diastereoand enantioselectivities,t he substituent R, attached to the nitrogen atom of the guanidine unit of 1,w as modified (entries [6][7][8][9]. [11] Theu se of excess NaN(SiMe 3 ) 2 relative to (M)-1a·HBr,which was employed in the a-amination of tetralones, [7a,b] had adetrimental effect on the enantioselectivity (entry 2v ersus entry 6).…”

(R,R)-1,2-Bis(aminocarbonylphenyl-2′-diphenylphosphino)cyclohexane

“…64 Reaction of a ketoester with isoprene monoepoxide was also effective in the synthesis of hyperolactone C and (−)-biyouyanagin A (here the naphthyl ligand was superior to the standard ligand). 65 The regio-and enantioselectivities have been reported for the reaction of isoprene monoepoxide with a range of ketoesters. 66 (20) Reaction of a 4-hydroxypyridone with an enantioenriched pyranone gave the tricyclic product (eq 21) in high ee, an intermediate in the synthesis of antitumor agent TMC-69-6H.…”