A sequential three-component process is described, starting from 3-arylmethylene-2,5-piperazinediones and involving a one-pot sequence of reactions achieving regioselective opening of the 2,5-diketopiperazine ring and diastereoselective generation of an aziridine ring. This method allows the preparation of N-unprotected, trisubstituted aziridines bearing a peptide side chain under mild conditio...

2-(2-Cyano-2-phenylethyl)aziridines were converted into novel trans-2-aminomethyl-1-phenylcyclopropanecarboxamides via regiospecific ring opening and 3-exo-tet cyclisation, thus providing the first convenient entry into the trans-isomer of Milnacipran as a useful template for further derivatisation. Furthermore, unprecedented 2-aminomethyl-1-benzylcyclopropanecarboxamides have been synthesized ...

A regio- and stereoselective method has been developed for the synthesis of novel fluorinated 2-aminocyclohexanecarboxylic acid derivatives with the fluorine attached to position 4 of the ring. The synthesis starts from either cis- or trans-β-aminocyclohex-4-enecarboxylic acids and involves regio- and stereoselective transformation of the ring C-C double bond through iodooxazine formation and h...

Mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates (1), obtained from the reaction of N-acyl-N-alkylglycines (2) with trifluoroacetic anhydride, react with ammonia to give 4-trifluoromethyl-3,4-dihydroimidazoles (3) in high yields. Dehydration of 3 gives 4-trifluoromethylimidazoles (4) in high yields. The novel ring transformation of 1 into 3 occurs via a regioselective attack of ammonia on the...

The fused 2-vinyl or 2-phenyl substituted cyclobutanones 4 undergo stereoselective ring openings by the action of alkoxide ions (t-BuO(-) or MeO(-)) to produce novel vicinally disubstituted cycloalkene derivatives 5 and 6 in moderate to high yields. The ring cleavage usually occurs with complete regioselectivity. The accessibility of γ,δ-unsaturated ester or acid derivatives makes this transfor...

An enantioselective alkoxylation/Claisen rearrangement reaction was achieved by a strategic desymmetrization of 1,4-dienes under the catalysis of (S)-DTBM-Segphos(AuCl)2/AgBF4. This reaction system was highly selective for the formation of 3,3-rearrangement products, providing cycloheptenes with various substitutions in good yield and good to excellent enantioselectivity. This transformation wa...

The family of algebraic graphs A(n;K) defined over the finite commutative ring K were used for the design of different multivariate cryptographical algorithms (private and public keys, key exchange protocols). The encryption map corresponds to a special walk on this graph. We expand the class of encryption maps via the use of an automorphism group of A(n,K). In the case of characteristic 2 the ...

Reaction of 2-thiocarbamoyl thiazolium salts with dimethyl acetylenedicarboxylate proceeded via a tandem [3+2] cycloaddition and a unprecedented ring transformation to produce functionalized thieno[2,3-b]pyrazine derivatives in good to excellent yields.

Transformation of self-assembled InAs quantum dots (QDs) on InP(100) into quantum rings (QRs) is studied. In contrast to the typical approach to III--V semiconductor QR growth, the QDs are not capped to form rings. Atomic force micrographs reveal a drastic change from InAs QDs into rings after a growth interruption in tertiarybutylphosphine ambient. Strain energy relief in the InAs QD is discus...

Let D be a domain in the complex plane (Riemann sphere) and R(D) the totality of one-valued regular analytic functions defined in D. With the usual definitions of addition and multiplication R(D) becomes a commutative ring (in fact, a domain of integrity). A oneto-one conformai transformation f =0(z) of D onto a domain A induces an isomorphism ƒ—>ƒ* between R(D) and R(A):f(z) =ƒ*[(2)]. An an...