Chiral Inductive Diastereoconvergent Allylation Reactions of Allyltrimethylsilane and Diastereomixtures of Diarylmethanols Catalyzed by FeCl₃

Abstract

We report the chiral‐auxiliary‐controlled diastereoconvergent allylation reactions of allyltrimethylsilane with diastereomeric mixtures of diarylmethanols in the presence of FeCl3 as a Lewis acid catalyst. This reaction was successfully applied to a variety of substrates; it proceeded irrespective of the substituent on the aromatic ring of the substrate. The present method was used as the key step in synthesizing (R)‐tolterodine.

Diastereoconvergent Dehydrative Nucleophilic Substitutions of Diastereomeric Diarylmethanols with 1,3‐Dicarbonyls Catalyzed by SnBr4

“…The reaction was complete within 1 h, and the desired product 12a was obtained in 83 % yield and with a 97:3 dr (entry 1). We have already reported on the applicability of tin salts as Lewis acids for the diastereoconvergent coupling reactions of 3a with several nucleophiles . Thus, the same reaction was conducted in the presence of several tin salts, namely, SnCl 2 , SnBr 2 , SnCl 4 , and SnBr 4 .…”

“…Diarylmethyl cation int‐2 is generated by activation of the hydroxy group on the diarylmethanol A with SnBr 4 , as shown in step (a), followed by subsequent elimination of the hydroxy group in step (b). It is expected that int‐2 is stabilized by chelation of the oxygen atom of the MeO group on the chiral auxiliary, and its conformation is controlled to form a seven‐membered ring transition state , . TLC analysis shows that there is a partial equilibrium between int‐2 and homoether AA , derived from 2 equivalents of A .…”

“…On the other hand, many related organocatalytic enantioselective syntheses utilizing quinone methides have been developed, but they are often restricted to substrates containing electron‐donating groups. Preceding this research, we developed a chiral auxiliary and applied it to Lewis acid‐catalyzed chiral inductive diastereoconvergent couplings of diarylmethanol diastereomeric mixtures 3 , employing nucleophiles such as 2‐naphthols, allyltrimethylsilane, benzamides, and sodium sulfinates . It was revealed that these reactions were applicable to a variety of substrates to give products 4 , 5 , 6 , and 7 , respectively (Scheme b).…”

Diastereoconvergent Synthesis of Chiral Diarylmethyl Sulfones by Direct Sulfonylation of Diarylmethanols Diastereomixtures with Sodium Sulfinates Catalyzed by SnBr2

“…However, almost all previously reported reactions afforded racemic mixtures and the extension to asymmetric substrates remains difficult. Therefore, we have recently developed Lewis acid catalyzed chiral inductive diastereoconvergent reactions of diarylmethanols diastereomixtures 3 bearing a chiral auxiliary with 2‐naphthols, allyltrimethylsilane, and benzamides . Furthermore, the stereoconvergent chiral inductive diastereodivergent sulfonamidation reaction of 3 was reported with sulfonamine to afford 7a and 7b using different Lewis acids (Scheme b).…”

Stereoconvergent Chiral Inductive Diastereodivergent Sulfonamidation of Diastereomixtures of Diarylmethanols with Sulfonylamine Catalyzed by Lewis Acids

“…However, since almost all previously reported reactions proceed in an S N 1 manner via a carbocation intermediate, expanding this reaction to its asymmetric version is still challenging. Given such research background, we have recently achieved the Lewis acid catalyzed chiral inductive diastereoconvergent reactions of diastereomixtures of diarylmethanol 3 , bearing a designed chiral auxiliary, with 2-naphthol derivatives or allyltrimethylsilane (Scheme b). Therefore, herein we attempted to apply sulfonylamines as a nucleophilic agent for extending the reaction to the asymmetric version (Scheme c).…”