Fix and Relax Heuristic for a Stochastic Lot-Sizing Problem

This paper addresses a particular stochastic lot-sizing and scheduling problem. The evolution of the uncertain parameters is modelled by means of a scenario tree and the resulting model is a multistage stochastic mixed-integer program. We develop a heuristic approach that exploits the specific structure of the problem. The computational experiments carried out on a large set of instances have shown that the approach provides good quality solutions in a reasonable amount of time.     

Reactions of 1,1,2,2-tetrafluoroethyl-N,N-dimethylamine with linear and cyclic 1,3-diketones

Ketones are known to be unreactive toward α-fluoroamines such as Ishikawa's Reagent or 1,1,2,2-tetrafluoroethyl-N,N-dimethylamine (TFEDMA). On the other hand, 1,3-diketones were found to undergo fluorination with TFEDMA. In the case of linear 1,3-diketones, the proposed mechanism involves the formation of β-fluoro-α,β-unsaturated ketones followed by the addition of HF to selectively give the product β,β-difluoroketone. Interestingly, when the 1,3-diketone is cyclic (i.e. 1,3-cyclohexadione) the outcome of the reaction is different and results in the formation of a product with a 2,2-difluoroacetyl group on the 2-carbon.     

A new efficient synthetic methodology for tetrahydroisoquinoline and tetrahydro-β-carboline derivatives using the Pictet–Spengler reaction

A new solution-phase methodology microwave-assisted for improving the Pictet-Spengler reaction in the synthesis of the tetrahydroisoquinoline and beta-carboline derivatives has been reported. This methodology was applied to obtain a small library of tetrahydroisoquinoline and beta-carboline derivatives using L-Dopa, dopamine, and tryptophan, as well as a variety of commercially available aldehydes as starting material. The use of such nonconventional reaction conditions reveals several features like a short reaction time compared to conventional eating, ease of isolation of the products after work-up, and improvement of the yields. This new one-pot protocol would be an ideal and rapid method to synthesize compounds in a combinatorial context.     

Novel transformations in the quassin series

A series of remarkable rearrangement reactions involving (1β,9β)-1-methoxypicras-11-en-16-one and related derivatives are described.     

REFIR/BB initial observations in the water vapour rotational band: Results from a field campaign

There is a growing interest in the far infrared spectral region 17-50 μm as a remote sensing tool in atmospheric sciences, since this portion of the spectrum contains the characteristic molecular rotational band for water vapour. Much of the Earth energy lost to space is radiated through this spectral region. The Radiation Explorer in the Far InfraRed Breadboard (REFIR/BB) spectrometer was born because of the quest to make observations in the far infrared. REFIR/BB is a Fourier Transform Spectrometer with a sampling resolution of 0.5 cm⁻¹ and it was tested for the first time in the field to check its reliability and radiometric performance. The field campaign was held at Toppo di Castelgrande (40° 49′ N, 15° 27′ E, 1258 m a. s. l.), a mountain site in South Italy. The spectral and radiometric performance of the instrument and initial observations are shown in this paper. Comparisons to both (1) BOMEM MR100 Fourier Transform spectrometer observations and (2) line-by-line radiative transfer calculations for selected clear sky are presented and discussed. These comparisons (1) show a very nice agreement between radiance measured by REFIR/BB and by BOMEM MR100 and (2) demonstrate that REFIR/BB accurately observes the very fine spectral structure in the water vapour rotational band.     

Total synthesis of dl-mexicanin I and dl-linifolin A

The helenanolides mexicanin I(1) and linifolin A(4) have been synthesized from hydroazulenol 5, thereby confirming the original structural assignments.     

Synthesis of Allylic Sulfones and Their Conversion to Dienoic and Trienoic Acids

The Ramberg-Bäcklund² method for the construction of carbon-carbon double bonds should in principle allow for the conversion of allylic sulfono-acetates to their corresponding dienoic acids (e. g. 1 → 2). Similarly a 2,4-pentadienyl sulfonoacetate should permit access to a trienoic acid(e.g. 3 → 4).