BINOLs modified at 3, 3′-positions: chemists’ preferred choice in asymmetric catalysis

Abstract

This article provides a general overview of the most relevant topics in the applications of BINOL modified at the 3 and 3′-positions in asymmetric catalysis. A brief introduction to the chiral BINOL backbone so modified is given. A selection of the most outstanding uses of the catalysts according to the functional groups at the 3,3′-positions of BINOL backbones such as 3,3′-disubstituents of BINOLs, phosphoric acid derivatives and phosphoramidites is then presented. This review aims to introduce the latest developments of this active field, including the literature since 2008.

Electrostatically Enhanced Thioureas

“…Small molecule metal-free hydrogen-bond catalysis has become an active and vibrant research area over the past two decades . Numerous classes of compounds have been explored including binols, silane diols, squaramides, , and α,α,α,α-tetraaryl-1,3-dioxolane-4,5-dimethanols (TADDOLs) among others, but no species have received more attention than thioureas . Of these, N , N ′-bis­(3,5-bis­(trifluoromethyl)­phenyl)­thiourea [(3,5-(CF 3 ) 2 C 6 H 3 NH) 2 CS], also known as Schreiner’s thiourea, occupies a privileged position because it is an especially effective catalyst leading to relatively rapid transformations.…”

Synthesis of Naphthylpyridines from Unsymmetrical Naphthylheptadiynes and the Configurational Stability of the Biaryl Axis

“…From the obtained data, the half-life time and rotational barriers can be derived, as it was exemplified early on for 1,1′-binaphthyl and 1,1′-binaphthyl-2,2′-diol (BINOL) and later corroborated by theoretical calculations . Especially the configurational stability of BINOL, possessing a high barrier of rotation of up to Δ G ‡ = 158 kJ mol –1 , caused by the tetra- ortho -substituted biaryl system has made it one of the most frequently utilized axially chiral structure elements for synthetic and catalytic purposes …”

Regioselective Substitution of BINOL

“…Remarkable regioselectivity has been observed in these reactions which has allowed the selective introduction of functional groups at the 6-, 5-, 4-, and 3-positions for the construction of many appealing chiral structures for diverse applications. The ortho-lithiation of BINOL at the 3-position has allowed the introduction of a variety of functional groups at this position and has been extensively used in modifying the steric and electronic environment of asymmetric catalysts and molecular hosts. , In recent years, transition metal-catalyzed C–H bond activation has also been utilized to functionalize BINOL at the 3-, 4-, 5-, 6-, and 7-positions with high regioselectivity. This paper will focus on reviewing these three types of regioselective substitution of the optically active BINOL.…”