Over the past decade, organocatalysis has seen tremendous development and become an important area in organic synthesis. Asymmetric organocatalysis employing chiral organic acids and bases as catalysts provided complementary catalytic activity comparing with metal catalysis. The features such as operational simplicity, easy catalyst recovery, environmental benignity as well as low toxicity often associated with organocatalysis make it very attractive. Organocatalysis has been widely used in total synthesis of natural products and pharmaceutical molecules. Several selected examples of the application of organocatalysis in total synthesis are included in Chapter I.

In the following chapters, four new organocatalytic reactions for stereoselective synthesis of useful building blocks have...[ Read more ]

Over the past decade, organocatalysis has seen tremendous development and become an important area in organic synthesis. Asymmetric organocatalysis employing chiral organic acids and bases as catalysts provided complementary catalytic activity comparing with metal catalysis. The features such as operational simplicity, easy catalyst recovery, environmental benignity as well as low toxicity often associated with organocatalysis make it very attractive. Organocatalysis has been widely used in total synthesis of natural products and pharmaceutical molecules. Several selected examples of the application of organocatalysis in total synthesis are included in Chapter I.

In the following chapters, four new organocatalytic reactions for stereoselective synthesis of useful building blocks have been described.

Chapter II describes the development of a highly efficient asymmetric synthesis of dihydronaphthalenes. The process represents a new addition to the limited asymmetric reactions of isobenzopyryliums, a family of versatile 10π aromatic species. Excellent asymmetric induction can be achieved for the first time without an anchoring group on the 4-position or a metal catalyst that was previously required in these reactions. The success is attributed to the unusual chiral counter anion (meanwhile also the nucleophile) generated in situ from the chiral phosphate and the boronic acid as well as the leaving group. Preliminary control experiments provided important insight into the reaction mechanism.

Chapter III introduces the development of the first efficient intermolecular addition of nitroalkanes to activated enynes for asymmetric synthesis of 2,3-allenoates. It is a new addition to the limited available strategies for catalytic asymmetric synthesis of allenoates. Enabled by a new bifunctional catalyst, a range of tri-substituted allenoates can be obtained in excellent chemical and optical purity. These allenoate products with a pendant 2-nitroethyl α-substituent are useful building blocks.

Chapter IV describes the development of the first organocatalytic enantio- and diastereoselective formal [3+2] annulation between imines and 1,4-dithiane-2,5-diol. The reactions proceed under mild conditions to form a range of thiazolidines with two stereocenters in excellent yields and with moderate to good stereoselectivity. This process employs readily available starting materials and catalyst, thus providing an attractive strategy for rapid construction of thiazolidine scaffolds.

Chapter V introduces the development of an organocatalyzed strategy for the efficient and diastereoselective synthesis of 3-amino-1-indanols, a privileged skeleton of significant importance in organic synthesis and medicinal chemistry. Under mild and basic conditions, the current reaction is complementary to the conventional Friedel–Crafts strategy, in which strong acidic conditions are employed and the cyclization step highly depends on the substrate electronic environment. Without modification, the standard conditions can be applied to the synthesis of enantioenriched 3-amino-1-indanols using a cleavable chiral sulfinamide nucleophile.