Pnictogen?Bonding Catalysts, Compared to Tetrel?Bonding Catalysts: More Than Just Weak <i>Lewis</i> Acids
نویسندگان
چکیده
A hyperresponsive tool to assess supramolecular catalysis, the cyclization of di-epoxides into cyclic ethers is used elucidate difference between pnictogen-bonding and Lewis acid catalysis systematically. For all stereoisomers, most tested catalysts follow Baldwin rules. Brønsted anion–? afford almost only products. acids such as SbCl3, BF3 BiCl3 give poorest selectivity, with at least 50 % (B) products for stereoisomers. In clear contrast, optimized operating on Sb(III) Sb(V) level fused anti-Baldwin (A) bicycles main product trans epoxides, independent syn or anti relation two epoxides. cis series, BA exclusively diastereomers, while diastereomers equal amounts AB show similarly special trends. These unique characteristics support that differs from can arguably be defined its non-covalent counterpart, just like hydrogen-bonding understood appreciated counterpart catalysis. Computational studies origin selectivity reveal an introvert deep ? hole surrounded by planar ring ligands. Central pnictogen-bond attraction against peripheral steric repulsion then forces epoxide break open. transient antimony oxidation in intermediates accounts chemoselectivity catalysts. Presumably due insufficient accessibility their holes, activity tetrel-bonding negligible. The division powerful irrelevant does not exist respective orthodox thus supports ?-hole are same.
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ژورنال
عنوان ژورنال: Helvetica Chimica Acta
سال: 2022
ISSN: ['1522-2675', '0018-019X']
DOI: https://doi.org/10.1002/hlca.202200119