The enantiomeric decahydro-2-iiaphthaleiiols (+)-S and (-)-S were prepared by enantloselective hydrolysis of the raceink chloroacetate ( i ) -2 catalyzed by porcine pancreatic lipase, and converted to the corresponding acetates (+)-1 and (-)-1 and ketones (+)-6 and (--)-6. The absolute configurations or the ketones, alcohols, and acetates were establishcd by chemical corrclation with natural manool ((+)-7) by making use of a refro-ene cleavage reaction of the known manool degradation product 8 to (-)-6. A distinct odour difference bctween the two enmtiomers of each pair (+)-l/(--)-l and (+)-6/(-)-6 has been round.

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The twelve bridged analogues 8 ± 19 of floral-type odorants related to cyclamenaldehyde (1) were synthesized (Schemes 1 ± 5) to investigate the relationship between the structural and conformational features of these compounds and their odor properties. Comparison of the data from sensory evaluation and molecular modeling suggests that the side chain of both the unconstrained and the constrained active analogues is not extended (anti) but rather folded (gauche) in the −bioactive× conformation. However, it is mainly the nature of the substituents at the a position of the aldehyde function that critically influences the odor quality and strength. These studies provide new information that should aid ongoing efforts to develop models of odorantÀreceptor interactions.1. Introduction. ± A commercially significant class of floral-type odorants is represented by 3-, which all exhibit a desirable lily-of-the-valley (−muguet×) tonality. Though many other compounds with different functional groups (alcohols, hydroxyaldehydes, acetals) belong to this class of odorants, in the present work, we will focus on aldehydes related to compounds 1 ± 3. StructureÀodor relationships in this class of odorants, among others, have been reviewed [4]. A computational model for lily-of-the-valley-scented compounds, based on AM1 calculations, was proposed by Pelzer et al. [5], which distinguished between two structural fragments bearing either a carbonyl or a hydroxy functional group. More recently, conformational analysis of a series of −muguet×-type odorants was used to design and synthesize candidates anticipated to possess a lily-of-the-valley odor [6]. Interest in this group of compounds has also been stimulated by the demonstration that a mixture of Lilial ¾ (2) and Lyral ¾ 4 ) (4) [7], a compound related to hydroxycitronellal (5) and that also exhibits a characteristic −muguet× odor, was able to stimulate a heterologously expressed rat olfactory receptor protein, OR5, and to generate secondmessenger responses at submicromolar concentrations [8]. Shortly after, computer-

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Overview of turbofans noise prediction methods based on CFD computations The constant trend to increase bypass ratio in turbofan aircraft engines has led to an increase of the relative contribution of rotors to the overall engine noise. There is therefore a need for efficient and accurate prediction tools to achieve a silent design of the rotor components. Here is given an overview of the different aeroacoustic methods investigated by Snecma and used for prediction of tone interaction noise, broadband interaction noise and broadband fan self noise. Different levels of methods refinement, from various analytical models to steady and unsteady CFD, will be compared in terms of accuracy of prediction and computational cost. Examples of implementation of these methods on conventional turbofan and counter-rotating fan configurations will be presented.