Abstract

Syntheses of (1R,2S,3R,4S)-1,7,7-trimethyl-2-pyridin-2-ylmethylbicyclo[2.2.1]-heptane-2,3-diol (7), (1R,2S,3R,4S)-1,7,7-trimethyl-2-[(6-methyl)-pyridin-2-ylmethyl-bicyclo-[2.2.1]heptane-2,3-diol (13), and (1R,2S,2’R,4R)-1,7,7-trimethyl-2-piperidin-2-ylmethyl-bicyclo[2.2.1]heptan-2-ol (19b) from commercially available (d)-camphor (1) are described. Key steps of the syntheses involved substrate-controlled diastereoselective alkylation and platinum oxide-catalyzed hydrogenation reactions. These compounds, and other intermediate amino alcohols in their syntheses, were successfully utilized as ligands in enantioselective diethyl zinc (Et2Zn) addition to benzaldehyde with moderate enantioselectivity.

Highlights

  • Chiral amino alcohols are common precursors to many functional molecules [1]

  • We have described syntheses and structural characterization of six new camphor-based amino alcohols and diols

  • These compounds were utilized as ligands for enantioselective additions of Et2Zn to benzaldehydes to obtain 1-phenylethanols

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Summary

Introduction

The chelate is capable of catalyzing enantioselective additions of organozincs to aldehydes [2]. The first ligand, (S)-leucinol, used to catalyze the addition of diethylzinc (Et2Zn) to benzaldehyde gave moderate enantioselectivity (49%) as reported by Oguni and Omi in 1984 [3]. In continuation of our ongoing research on the design and synthesis of new chiral ligands for asymmetric reactions [25], we are reporting syntheses of new amino alcohols and amino diols derived from (+)-camphor. The utility of the new ligands for the addition of Et2Zn to benzaldehyde was studied briefly

Result and Discussion
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