Etudes sur les composés organométalliques. XIX. Synthèse et caractérisation de composés alkoxy (alkyl)titane (IV)

Studies of Organometallic Compounds. Synthesis and Characterization of Some Alkoxy (alkyl)-titanium(IV) Compounds Alkoxy(benzyl)titanium and alkoxy(cyclohexyl)titanium compounds are prepared by alcoholysis of tetrabenzyl- and tetracyclohexyltitanium. Structural features are investigated by means of ¹H-NMR.     

A Chemical Study of Virginia Tobacco Flavour (Nicotiana Tabacum L.). I. Isolation and Synthesis of Two Bicyclodamascenones

Aged Virginia tobacco was steam-distilled and the resulting condensate investigated by chromatographic methods. This allowed identification of the bicyclodamascenones A and B in a small subfraction from this condensate. Both these ketones, which are novel tobacco constituents, were also synthesized and a possible mechanism is proposed for their formation via acid-catalysed cyclization of β-damascenone ( 1 ).     

Transposition des cycles satures en spectrometrie de masse II–Ethylene acetals derives de cyclopentanones et de cyclohexanones

The detailed study of the mass spectra of cyclopentanone and cyclohexanone acetals produces new evidences for the rearrangement of the corresponding molecular ions. The rearrangement was quantitatively studied with the help of a simple model. The influence of different structural features is discussed.     

The Whitney embedding theorem for tropical torsion modules: Classification of tropical modules

We prove here a tropical version of the well-known Whitney embedding theorem [32] stating that a smooth connected m-dimensional compact differential manifold can be embedded into R^2m+1.The tropical version of this theorem states that a tropical torsion module with m generators can always be embedded into the free tropical module , where p (equals to 2 for m=2, and otherwise) is the number of rows supporting the torsion, when the generators are given by the (independent) columns of a matrix of size n×m.As a corollary, we get that tropical m-dimensional torsion modules are classified by a (m-1)(m(m-1)-1)-parameter family.     

Synthesis of (R)- and (R)-4-methyl-6-2′-methylprop-1′-enyl-5,6-dihydro-2H-pyran (Nerol oxide) and Natural Occurrence of its Racemate

Following a known procedure, a mixture of (?)-(2S,3R)- and (+)-(2R,3R)-2,3-epoxy-citronellols ( 5 ) was prepared from (?)-(R)-linalool ( 3 ) via epoxy alcohol 4 and then reduced to (?)-(R)-3-hydroxy-citronellol ( 6 ). Sensitized photooxygenation of (?)-(R)-diol 6 led in part to (?)-(R)-triol 8 which was cyclodehydrated by dilute acid to a mixture of diastereoisomeric tetrahydropyran-4-ols 9 and 10 . Dehydration of hydroxy ethers 9 and 10 afforded (?)-(S)-nerol oxide ( 11 ) and (+)-(R)-nerol oxide ( 12 ), respectively, with an optical purity of 91%. Nerol oxide isolated from Bulgarian rose oil (0.038%) proved to be racemic. These results shed some light on the formation of nerol oxide in plants.     

Etudes sur les composés organométalliques. Partie XXI. Contribution à l'étude de la décomposition du tétracyclohexyltitane

Studies on Organometallic Compounds. Contribution to the Study of Thermal Decomposition of Tetracyclohexyltitanium Thermal decomposition of tetracyclohexyltitanium proceeds in a different manner for the solid compound and for etheral solution. We propose an explanation of the decomposition mechanisms based on radical reactivities and compare our results with previous literature data.     

Identification de la damascénone et de la β-damascone dans le tabac Burley

The successful identification of damascenone (I)

1 DORICENONE (trade mark of Firmenich & Cie, Geneva).

and β-damascone (III)

2 DORINONE (trade mark of Firmenich & Cia, Geneva)

in Burley tobacco oil was achieved through the use of an efficient vapour phase chromatography/mass spectrometry combination. Thus, the occurrence of β-damascone in nature and the presence of damascenone in an essential oil not related to rose oil were demonstrated.     

A Chemical Investigation of the Volatile Constituents of East Indian Sandalwood Oil (SantalumalbumL.)

Distillation foreruns from East Indian sandalwood oil (Santalum album L .), representing 5–8% of the oil, have been investigated using fractional distillation, preparative column chromatography, gas liquid chromatography (GLC.), and chemical treatments. This allowed the isolation and characterization by their spectral data of 46 compounds. 32 of them were newly identified sandalwood oil constituents including 4 novel substances: santalone ( 2 ), 4-methylcyclohexa-1,3-dien-1-yl methyl ketone ( 4 ), 5,6-dimethyl-5-norbornen-exo-2-ol ( 7 ), and (E)-5-(2,3-dimethyl-3-nortricyclyl)-pent-3-en-2-one ( 20 ). The other constituents identified were 1-furfuryl-pyrrole ( 10 ) and 10 phenols accompanied by 17 terpene and sesquiterpene derivatives. Endo-2,endo-3-dimethyl-norbornan-exo-2-ol ( 6 ), an α-santenol ( z ), precursor, was present in the last group of constituents. The compounds 2, 4, 6, 7, 20 have been synthesized as well as another novel constituent, endo-2-mythyl-3-methylidene-norbornan-exo-2-ol ( 5 ).     

The stereospecific synthesis of all four stereoisomers of 2-amino-6-phenoxy-cyclohexanol,

Epoxidation of 3-phenoxycyclohexene 5 with m-chloro-perbenzoic acid gave 6 and 7 in a ratio of 9:1. These two epoxides were heated with a series of amines to give the aminophenoxycyclohexanol derivatives 1 and 2 respectively; in all cases the reaction was regio- and stereospecific. Two methods based on the principle of neighbouring group participation were developed to synthesize the cis-amino alcohols 3 and 4 . In the first, the hydroxy group was used to introduce an amine function at the vicinal carbon atom. In the second method, the amino group served as the point of reference and the configuration of the adjacent alcohol function was inverted.