Recent Advances inCinchonaAlkaloid Chemistry

Abstract

Quinine has been among the best known alkaloids for over 300 years, thanks to its antimalarial activity. In the last two decades, Cinchona alkaloids have emerged as powerful chiral auxiliaries, resulting in some well known landmark developments in asymmetric synthesis, but more recently these alkaloids themselves have been shown to undergo some remarkable transformations and skeletal shifts that are rapidly widening perspectives in the chemistry of Cinchona bases, embracing both basic and applied science. The alkaloids enter into a series of fundamental transformations that have given rise to the industrial manufacture of a host of new enantiopure materials showing promise for asymmetric syntheses and combinatorial chemistry. Stereochemical diversity, well developed conformational minima not encountered in conventional organic substrates, hydrophilic pockets and stereoelectronics contribute subtle mechanistic features and structural complexity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Recent applications of Cinchona alkaloids and their derivatives as catalysts in metal-free asymmetric synthesis

“…2) have been employed as catalysts in many well-known reactions affording diverse types of enantiopure products (Fig. 3) 13 many of which have been employed as key structural units in the synthesis of other complex natural products. Before the submission of this article, two representative review articles appeared on this topic in 2001 and 2004 (covering research up to 2003).…”

The Physico-chemical Properties of Cinchona Alkaloids Responsible for their Unique Performance in Chiral Catalysis

“…Cinchona alkaloids, compounds found naturally in the bark of cinchona trees, are used in a number of diverse applications, including the treatment of malaria [1] and cardiac arrhythmias [2], as additives in soft drinks [3], as starting materials for organic synthesis [4], and as chiral resolving agents in fractional crystallization [5] and chromatographic [6] techniques. They have also shown great promise for the promotion of enantioselectivity in both homogeneous [7] and heterogeneous [8] catalysis.…”

Quinine‐Derived Imidazolidin‐2‐imine Ligands: Synthesis, Coordination Chemistry, and Application in Catalytic Transfer Hydrogenation

“…In particular, cinchona alkaloids and their derivatives, such as quincorine and quincoridine, which are relatively cheap and readily available in both pseudo-enantiomeric forms, were used [3]. These two pseudo-enantiomeric 1,2-amino alcohols, quincorine [QCI = (2S,4S,5R)-2-hydroxymethyl-5-vinyl-2-quinuclidine] and quincoridine [QCD = (2R,4S,5R)-2-hydroxymethyl-5-vinyl-2-quinuclidine] have four stereogenic centers, including the (1S)-configured bridgehead nitrogen atom [4].…”