Alcohols and phenols as hydrogen bonding catalysts

Abstract

Hydrogen-bonding catalysis has been a rapidly growing field of organocatalysis and has found numerous applications in a broad range of organic transformations. In this chapter, applications of hydrogen bonding catalysts based on alcohols and phenols will be covered with emphasis on catalyst design and mechanistic investigations. The first part of this chapter describes the development of alcohol-based hydrogen-bonding catalysts. Chiral hydrogen bond donors such as TADDOL and BAMOL derivatives have been shown to be highly effective catalysts in a variety of enantioselective transformations including Diels–Alder, hetero-Diels–Alder, Mukaiyama aldol, and nitroso aldol reactions. A photoswitchable hydrogen-bonding catalyst system that was used in a Morita–Baylis–Hillman reaction was also described in this section. Efforts to enhance the activities of alcohol-based hydrogen bond donors resulted in the development of fluorinated alcohols as effective organocatalysts. The second part of this chapter describes the utilization of such fluorinated alcohol catalysts in ring-opening polymerization of lactides, carbon dioxide fixation of epoxides, and epoxidation of alkenes. Finally, hydrogen-bonding catalysts based on phenols are reviewed in the third section of this chapter. These include dual hydrogen bond donors such as PHANOL, diarylacetylene diol, and BINOL derivatives along with examples from enantioselective catalysis.