Enantioselective organo-SOMO catalysis has, in the last two years, been the subject of considerable development and exploration. A number of new and unique transformations have been reported, such as alpha-allylation, alpha-oxyamination, alpha-enolation, and alpha-vinylation of aldehydes. Herein, we report a modification of this activation mode that involves the intramolecular Friedel-Crafts-type alpha-arylation of aldehydes carrying electron-donating groups on their aromatic nucleus and its application to the total synthesis of demethyl calamenene, a potent cytotoxic agent against human adenocarcinoma A 549.

An efficient, organocatalytic enantioselective synthesis of N-arylsulfonyl a-amino nitriles from the corresponding a-amido sulfones has been developed. This quinine-catalyzed Strecker reaction provides the corresponding cyanated products in good yields and enantioselectivities.Keywords: asymmetric cyanation; chiral pool; organocatalysis; potassium cyanide; quinines; Strecker reactionThe catalytic asymmetric cyanation of imines, the socalled Strecker reaction, [1] is one of the most powerful and efficient strategies for the synthesis of chiral a-amino acids and their derivatives. In the last decade, both metal-catalyzed [2] processes and organocatalytic approaches [3,4] have been developed for this purpose and a large number of highly successful and efficient protocols, providing a reliable access to a wide range of optically active a-amino nitriles, have been reported.[5] However, more efforts are still needed in this area, because the highly efficient cyanation of imines to afford the precursors of pharmaceutically important a-amino acids is always prevailing and the quest for a universal and powerful organocatalytic system which avoids the use of hazardous and expensive cyanation agents like TMSCN or HCN still remains a challenge.Herein, we present an enantioselective cyanation of several N-carbamoyl aldimines, in situ generated from a-amido sulfones 1, [6] promoted by the powerful and naturally occurring alkaloid quinine (2) [4] using potassium cyanide (KCN) as a safe and convenient cyanating agent (Scheme 1).The required N-carbamoyl a-amido sulfone 1, a synthetic precursor of the corresponding aldimines, can be readily prepared from aldehydes and the corresponding carbamate following known protocols in the literature, and easily purified by recrystallization. [7] As a model reaction, we investigated the reactivity of the representative substrate 1a, which can easily be synthesized from benzaldehyde, tert-butyl carbamate and NaSO 2 Ph. To avoid the highly toxic and volatile HCN, we used potassium cyanide (KCN), a more convenient cyanation reagent, which is easier to handle. In this process, KCN plays two roles. It first acts as a base, liberating the free N-carbamoyl imine by deprotonation of precursor 1 and subsequent elimination of Scheme 1. Organocatalytic Strecker reaction with quinine.

Page 15807. A typographical mistake was found in eq 1. The correct form of the Henderson-Hasselbalch equation for deprotonation should readwhere δ obs is the observed chemical shift and δ HA and δ A -are the chemical shifts of the protonated and unprotonated forms, respectively.Importantly, all data were analyzed with this correct form of eq 1, and in no way does this correction change the results or conclusions presented in the original paper. We thank Mr. Jelle Slager for bringing this mistake to our attention.

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The stability of various substituted aryl-3,3-dialkyltriazenes, valuable synthetic intermediates, under several reaction conditions has been evaluated. To do so, anthranilonitrile and 2-amino-6-(trifluoromethyl)benzonitrile have been reacted in the presence of different secondary amines to the corresponding 1-(2-R-phenyl)-3,3-dialkyltriazenes. These compounds have been submitted to a series of different reaction conditions with special emphasis on strong basic and metal/ acid reductive conditions in order to test the stability of the triazene moiety under these circumstances. Generally, triazenes are unstable in metal/acid reducing conditions. A lot of 1-aryl-3,3-dialkyltriazenes are known to undergo deprotonation in α-position of N-3 in the presence of strong bases, thus limiting the scope of action of this class of compounds.