“Design” of Boron‐Based Compounds as Pro‐Nucleophiles and Co‐Catalysts for Indium(I)‐Catalyzed Allyl Transfer to Various Csp3‐Type Electrophiles |
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Authors: | Hai Thanh Dao Dr. Uwe Schneider Prof. Dr. Shū Kobayashi |
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Affiliation: | Department of Chemistry, School of Science, The University of Tokyo, The HFRE Division, ERATO (Japan) Science and Technology Agency (JST), Hongo, Bunkyo‐ku, Tokyo 113‐0033 (Japan), Fax: (+81)?3‐5684‐0634 |
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Abstract: | We have recently uncovered a general indium(I)‐catalyzed method for allylations and propargylation of acetals and ketals with a water‐ and air‐stable allyl boronate. By using a more reactive allyl borane, we have successfully extended this methodology to the more challenging C C coupling with ethers. Herein, we report an improved methodology for the indium(I)‐catalyzed allylation of acetals and ethers, through combination of the allyl boronate with a commercially available “hard” Lewis acid, B‐methoxy‐9‐BBN (BBN=borabicyclo[3.3.1]nonane), as an effective co‐catalyst. Significantly, our work highlights for the first time the correlation between the Lewis acidity of “electrophilic” boron‐based compounds and their “nucleophilic” reactivity in Csp3–Csp3 couplings, catalyzed by a “soft” low‐oxidation main group metal. In addition, we also report several applications of these methodologies to the selective synthesis of various carbohydrate derivatives. |
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Keywords: | allylation boron carbohydrates C?C coupling indium |
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