| Autor: |
Liang T; Department of Chemistry, University of Texas at Austin , 1 University Station, Welch Hall A5300, Austin, Texas 78712, United States., Zhang W; Department of Chemistry, University of Texas at Austin , 1 University Station, Welch Hall A5300, Austin, Texas 78712, United States., Chen TY; Department of Chemistry, University of Texas at Austin , 1 University Station, Welch Hall A5300, Austin, Texas 78712, United States., Nguyen KD; Department of Chemistry, University of Texas at Austin , 1 University Station, Welch Hall A5300, Austin, Texas 78712, United States., Krische MJ; Department of Chemistry, University of Texas at Austin , 1 University Station, Welch Hall A5300, Austin, Texas 78712, United States. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of the American Chemical Society [J Am Chem Soc] 2015 Oct 14; Vol. 137 (40), pp. 13066-71. Date of Electronic Publication: 2015 Sep 29. |
| DOI: |
10.1021/jacs.5b08019 |
| Abstrakt: |
The first enantioselective carbonyl crotylations through direct use of alkynes as chiral allylmetal equivalents are described. Chiral ruthenium(II) complexes modified by Josiphos (SL-J009-1) catalyze the C-C coupling of TIPS-protected propargyl ether 1a with primary alcohols 2a-2o to form products of carbonyl siloxy-crotylation 3a-3o, which upon silyl deprotection-reduction deliver 1,4-diols 5a-5o with excellent control of regio-, anti-diastereo-, and enantioselectivity. Structurally related propargyl ethers 1b and 1c bearing ethyl- and phenyl-substituents engage in diastereo- and enantioselective coupling, as illustrated in the formation of adducts 5p and 5q, respectively. Selective mono-tosylation of diols 5a, 5c, 5e, 5f, 5k, and 5m is accompanied by spontaneous cyclization to deliver the trans-2,3-disubstituted furans 6a, 6c, 6e, 6f, 6k, and 6m, respectively. Primary alcohols 2a, 2l, and 2p were converted to the siloxy-crotylation products 3a, 3l, and 3p, which upon silyl deprotection-lactol oxidation were transformed to the trans-4,5-disubstituted γ-butyrolactones 7a, 7l, and 7p. The formation of 7p represents a total synthesis of (+)-trans-whisky lactone. Unlike closely related ruthenium catalyzed alkyne-alcohol C-C couplings, deuterium labeling studies provide clear evidence of a novel 1,2-hydride shift mechanism that converts metal-bound alkynes to π-allyls in the absence of intervening allenes. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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