Peter Stanetty

Monooxygenase-Mediated Baeyer−Villiger Oxidations

Enzyme-mediated Baeyer−Villiger oxidations offer a “green chemistry” approach for the production of chiral lactones. Several organisms have been found to catalyze this reaction in the course of their metabolic pathways. A number of flavin-dependent monooxygenases have been characterized, and acceptance of a multitude of non-natural substrates has been found. Such biocatalysts are used in synthetic chemistry either as isolated enzymes in combination with appropriate cofactor recycling systems or as living whole cells, in native or recombinant form, for the production of valuable intermediates. This review gives an overview of the most widely utilized enzymes and the corresponding substrate profiles, together with applications in natural product and bioactive compound synthesis. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Halogen dance reactions—A review

Halogen Dance (HD) reactions are a useful tool for synthetic chemists as they enable access to positions in aromatic and heteroaromatic systems for subsequent functionalization which are often difficult to address by other methods, hence, allowing entry to versatile scaffolds. While the method can be extremely useful, this transformation is often neglected upon designing synthetic sequences. This may be largely attributed to the lack of comprehensive reference works covering the general principles and outlining the versatility and limitations of the technique. The following review tries to present HD reactions in a clear and concise manner in order to convince more chemists of its advantages. It covers the field of HD reactions from their first observation in 1951 until the present. The important contributions leading to the elucidation of the mechanism are briefly outlined followed by a detailed mechanistic section and a discussion of factors which influence HD reactions. Finally, an overview of HD reactions on various carbocyclic and heterocyclic ring systems and its applications in the synthesis of complex compounds is given.

First enantiodivergent baeyer-villiger oxidation by recombinant whole-cells expressing two monooxygenases from Brevibacterium

Microbial Baeyer-Villiger oxidations of representative mesomeric ketones with recombinant Escherichia coli cells expressing two monooxygenases from Brevibacterium were investigated. The two enzymes displayed enantiodivergent biotransformations on an array of structurally diverse substrates, allowing access to some key lactone intermediates in natural compound synthesis.

Baeyer-Villiger oxidations of representative heterocyclic ketones by whole cells of engineered Escherichia coli expressing cyclohexanone monooxygenase

Whole cells of an Escherichia coli strain overexpressing Acinetobacter sp. NCIB 9871 cyclohexanone monooxygenase (CHMO; E.C. 1.14.13.22) have been used for the Baeyer-Villiger oxidation of representative heterocyclic six-membered ketones to probe the potential impact of nitrogen, sulfur and oxygen on the chemoselectivity of these reactions. The fact that all of these heterocyclic systems were accepted as substrates by the enzyme and gave normal Baeyer-Villiger products broadens the synthetic utility of the engineered E. coli strain and emphasizes the chemoselectivity achievable with enzymatic oxidation catalysts.

A facile and green synthetic route to boronic acid esters utilizing mechanochemistry

A facile and environmentally benign method for the formation of boronic acid esters from corresponding boronic acids is reported. Simple grinding of a 1 : 1 mixture of the boronic acid (alkyl, aryl, or heteroaryl boronic acid) and the diol (pinacol or 2,2-dimethylpropane-1,2-diol) without a solvent gave the boronic acid esters. A subsequent simple work-up step gave the title compounds in excellent yield and purity.

Über die Synthese von substituierten 5-Phenyl-1H-thieno[2,3-e]1,4-diazepin-2(3H)-onen

The preparation of in position 6 and 7 mono- and dimethylsubstituted 5-phenyl-1H-thieno[2.3-e]1.4-diazepin-2(3H)-ones and their methylation in position 1 are described. The thienodiazepine5 b was furthermore chlorinated, brominated and nitrated in position 7.ZusammenfassungEs wird die Synthese von in Stellung 6 und 7 mono- und dimethylsubstituierten 5-Phenyl-1H-thieno[2,3-e]1,4-diazepin-2(3H)-onen und ihre Methylierung in Stellung 1 beschrieben. Das Thienodiazepin5 b wurde außerdem in Stellung 7 chloriert, bromiert und nitriert.

Über die Synthese von substituierten 1,3-Dihydro-5-(2-pyridyl)-thieno[2,3—e]-1,4-diazepin-2-onen

The preparation of the title substances as well as their chlorination in position 7 and methylation in position 1 are described.

2,3-Dihydro-7-benzofurancarbonsäuren

SummaryThe syntheses of a series of title compounds1 a–f bearing methyl groups in the heterocyclic part were described. Depending on the substitution pattern the Claisen rearrangement (path A) or the methodology of directed lithiations (path B) were used as the key steps.

A novel hetero-Diels-Alder approach towards perhydro quinolinones bearing an angular methyl group

Abstract The title compounds 9–11 were synthesized by a hetero Diels-Alder reaction using the sterically demanding diene 2 as a new building block. The effect of commonly used Lewis acids and the substitution pattern of various imines 5 on both the mechanism and the diastereoselectivity of the reaction with the diene is discussed and compared with data obtained by ab initio calculations.

Cyclisierungsreaktionen zu Thiazolo[3,2—a]thieno[2,3-d]pyrimidinen

Cyclisation of 2-(β-oxo-alkylthio)-thieno[2.3-d]pyrimidin-4(3H)-ones gave separable mixtures of the title substances and their [2.3-b]-isomers. The structure of the two isomers were be proved by comparison with a linear product synthesized by an unambiguous method. Similar cyclisations were achieved by reactions of 2-mercapto-thieno[2.3-d]pyrimidin-4(3H)-ones with chloroacetone, 1.2-dibromoethane or 1.3-dibromopropane.