3-Amino-2-methylpyrrolidines were prepared via a novel protocol, involving the reductive ring closure and O-deprotection of gamma-acetoxy-alpha-chloroketimines towards 2-(2-hydroxyethyl)-3-methylaziridines, followed by ring expansion of the latter into 3-bromopyrrolidines via intermediate bicyclic aziridinium salts and consecutive nucleophilic displacement of the bromo atom by azide towards 3-a...

Ring torsion effects on optical excitation properties in poly(para-phenylene) (PPP) and polyaniline (PAN) are investigated by the intermediate exciton formalism. Long-range excitons are characterized, and the long-range component of the oscillator strengths is calculated. We find that ring torsions affect the long-range excitons in PAN more easily than in PPP, due to the larger torsion angle of...

ion or by sequential loss of a *-bond electron and a proton termed an aborted epoxidation by Ortiz de Montellano (1986) and indeed epoxidated products are generated by methane monooxygenase from these substrates (Table 111). Oxidation of Cyclopropylbenzem-Attaching a cyclopropyl ring to the hydroxylated carbon atom of a hydrocarbon substrate as a means of testing for the presence of carbon radi...

Synthesis of monoterpene indole alkaloids, leuconoxine, leuconodine B, and rhazinilam, by transformation melodinine E via 6-hydro-21-dehydroxyleuconolam was established. The pivotal intermediate, 6-hydro-21-dehydroxyleuconolam, prepared from a ring-opening N,S-acetal formation the diaza[5.5.6.6]fenestrane skeleton subsequent chemoselective reduction. These results demonstrate that 6-hydro-21-de...

Herein, we describe the synthesis, structural characterization, and synthetic use as an advanced intermediate of a cross-stapled alkene-bridged hexapeptide to mimic the DE-ring of the lantibiotic nisin. The linear precursor was cyclized by ring-closing metathesis to give the correctly folded bicyclic hexapeptide in a single step, and the four individual diastereoisomers were isolated, structura...

Fourteen different genes included in a DNA fragment of 18 kb are involved in the aerobic degradation of phenylacetic acid by Pseudomonas putida U. This catabolic pathway appears to be organized in three contiguous operons that contain the following functional units: (i) a transport system, (ii) a phenylacetic acid activating enzyme, (iii) a ring-hydroxylation complex, (iv) a ring-opening protei...

A simple, efficient and flexible strategy for the syntheses of cladospolides A-C and iso-cladospolide B is reported here. This strategy involves Julia-Kocienski olefination and Yamaguchi macrolactonization as key steps, starting from either d-ribose or suitable tartaric acid esters. Although our initial efforts towards cladospolide A involving a ring closing metathetic approach were not success...

A synthetic strategy for the modeling construction of the highly bridged azatetracyclic ABEF ring system of numerous lycoctonine-type C19-diterpenoid alkaloids bearing a characteristic oxygenated quaternary center at C-7 has been successfully developed. The tetracyclic core was constructed rapidly from a readily prepared 6,7-bicyclic AB ring precursor through a 13-step sequence via an advanced ...

We provide a tight security proof for an IND-CCA RingLWE based Key Encapsulation Mechanism that is derived from a generic construction of Dent (IMA Cryptography and Coding, 2003). Such a tight reduction is not known for the generic construction. The resulting scheme has shorter ciphertexts than can be achieved with other generic constructions of Dent or by using the well-known Fujisaki-Okamoto ...

A new synthetic strategy for the preparation of imidazo[1,2-a]pyridines 10 is reported, which is based on the electrocyclization reaction of imino pyridinium salts 7 upon treatment with a strong base. The starting materials are easily prepared from 2-aminopyridine (3) by imine condensation and subsequent alkylation at the pyridine nitrogen atom. The ring closure reaction of the zwitterionic int...