Chiral chelated lithium amides were designed and synthesized. Studies have been done to explore the use of these lithium amides or their corresponding amines for enantioselective reactions such as deprotonation of prochiral cyclic ketones, kinetic resolution of racemic 2-substituted cyclohexanones by deprotonation, regioselective deprotonation of optically active 3-keto steroids, alkylation of ...

[structure: see text] The asymmetric total synthesis of (-)-callystatin A has been achieved. The key steps generating the stereogenic centers rely on the asymmetric alpha-alkylation of aldehydes or ketones exploiting the SAMP/RAMP hydrazone alkylation methodology, as well as an enzymatic enantioselective reduction of a 3,5-dioxocarboxylate. For the construction of the alkene moieties, highly se...

The Escherichia coli Ada protein activates sigma(70)-dependent transcription at three different promoters (ada, aidB, and alkA) in response to alkylation damage of DNA. During stationary phase, however, the methylated form of Ada shuts off expression of alkA; this repression is specific for sigma(S)-dependent transcription. Thus, at the alkA promoter, the Ada protein can act as both a positive ...

Efficient catalytic asymmetric synthesis of 1,1-disubstituted tetrahydro-β-carbolines has been achieved via asymmetric alkylation of 1-cyanotetrahydro-β-carbolines using a binaphthyl-modified N-spiro-type chiral phase-transfer catalyst. This is a valuable example of hitherto difficult highly enantioselective alkylations at α-carbon of the cyano group under phase-transfer conditions.

An application of the classical Ritter reaction for the synthesis of unsymmetrical di and trisubstituted ureas catalyzed by FeCl(3) is described. The protocol is of significant interest in view of the easy availability of precursors, mild reaction conditions employed and interestingly its applicability for the alkylation of alcohols capable of forming stable carbocationic intermediates even to ...

An enantioselective desymmetrization of prochiral 1,3-dinitropropanes has been developed which proceeds via enantiogroup differentiating organocatalytic allylic alkylation. Densely functionalized products with two vicinal stereocenters were obtained generally with good to excellent diastereoselectivity (up to >20 : 1 dr) and superb enantioselectivity (up to >99 : 1 er).

Cells rely on the precise action of proteins that detect and repair DNA damage. However, gene expression noise causes fluctuations in protein abundances that may compromise repair. For the Ada protein in Escherichia coli, which induces its own expression upon repairing DNA alkylation damage, we found that undamaged cells on average produce one Ada molecule per generation. Because production is ...

Ruthenium phosphido complexes have been shown to be excellent nucleophiles, reacting via two-electron processes with a variety of electrophiles. A catalytic alkylation reaction was developed using an achiral ruthenium complex, which was then elaborated into a catalytic enantioselective synthesis of P-stereogenic phosphines. These useful and synthetically challenging phosphines can now be access...

Dihydroimidazo[5,1-c][1,2,4]triazine-3,6(2H,4H)-dione derivatives were prepared by successive N3- and N1-alkylation of hydantoins, followed by regioselective thionation and subsequent cyclization under mild conditions. In a final alkylation step a further substituent may be introduced. The synthetic strategy allows broad structural variation of this new drug-like heterobicyclic scaffold. In add...

Table of Contents General methods S1 Reagents and materials S2 General protocol for the preparation of starting chiral ynamides S3 General procedures for the allylation of stereodefined trisubstituted copper enolate S5 Optimization reactions S8 Products of the enantioselective allylic alkylation reaction S9 Cleavage of oxazolidinone moiety 4 S19 References S21 X-Ray crystallographic analysis da...