31503-04-5Relevant articles and documents
Thermal isomerization of isoborneols and dehydroisoborneols to new chiral building blocks in terpenoid synthesis
Rueedi, Georg,Hansen, Hans-Juergen
, p. 1968 - 1989 (2007/10/03)
The substituted isoborneols 1a-1g and 5,6-dehydroisoborneols 6a-6c, readily prepared in excellent yields from (+)-camphor and (+)-5,6-dehydrocamphor (2) by aryl, vinyl, or alkyl Grignard addition in the presence of stoichiometric amounts of CeCl3, were thermally isomerized in a flow reactor system under DGPTI (dynamic gas-phase thermo-isomerization) conditions at temperatures between 480 and 630° to give the enantiomerically pure monocyclic carbonyl compounds 7a-7d, 19a,b, 23, and 24. In all cases, product formation proceeded highly regio- as well as stereoselectively. The absolute configurations of the new stereogenic centers were determined by 1H-NOE measurements. DGPTI of the aryl substrates 1a-1d is proposed to effect initial cleavage of the weakest single bond in the molecule under formation of a diradical intermediate state followed by intramolecular H-abstraction to afford the acetophenone derivatives 7a-7d. This reaction path was further supported by a 2H-labeling study showing the OH group to be the exclusive H-source. In contrast, DGPTI of the vinyl substrates 1e and 6b allowed concerted retro-ene and oxy-Cope rearrangements. In the case of 5,6-dehydro-2-phenylisoborneol (6a), concomitant diradical and retro-Diels-Alder reaction pathways could be observed. In addition, a new route to (+)-rrans-a-campholanic acid (9) and (+)-trans-a-dihydrocampholytic acid (14) is presented by regioselective Baeyer-Villiger oxidation and subsequent hydrolysis of 7c and 7d, respectively.
Renewable camphor-derived hydroperoxide: Synthesis and use in the asymmetric epoxidation of allylic alcohols
Lattanzi, Alessandra,Iannece, Patrizia,Vicinanza, Assunta,Scettri, Arrigo
, p. 1440 - 1441 (2007/10/03)
Renewable enantiopure tertiary furyl hydroperoxide has been easily synthesized in two steps starting from low cost (+)-(1R)-camphor and it has been used in the asymmetric epoxidation and kinetic resolution of allylic alcohols (enantioselectivities up to 46%).
High purity (1R,2S,4R)-(-)-2-[(2′-{N,N-dimethylamino}-ethoxy)]-2-[phenyl]-1,7,7-tri-[methyl]-bicyclo[2.2.1]heptane and pharmaceutically acceptable acid addition salts thereof
-
Example 1, (2010/11/29)
The invention relates to high purity (1R,2S,4R)-(?)-2-[(2′-{N,N-dimethylamino}-ethoxy)]-2-[phenyl]-1,7,7-tri-[methyl]-bicyclo[2.2.1]heptane and pharmaceutically acceptable acid addition salts thereof containing not more than 0.2% of (1R,3S,4R)-3-[(2′-{N,N
Improved addition of phenyllithium to hindered ketones by the use of non-polar media
Lecomte, Vincent,Stéphan, Elie,Jaouen, Gérard
, p. 3463 - 3465 (2007/10/03)
The use of a non-polar medium at room temperature is an efficient, cheap and easy way to improve the low reactivity of six hindered ketones towards phenyllithium.
Asymmetric Conversion of Arenechromium Complexes to Functionalized Cyclohexenones: Progress toward Defining an Optimum Chiral Auxiliary
Pearson, Anthony J.,Gontcharov, Alexander V.
, p. 152 - 162 (2007/10/03)
An investigation into the asymmetric synthesis of 5-substituted cyclohexenones via nucleophile addition to (alkoxyarene)chromium tricarbonyl complexes is described. Diastereoselectivity during the nucleophile addition step was achieved using alkoxy substituents derived from terpenoid substrates as chiral auxiliaries. Selectivities as high as 24:1 were obtained when 2-phenylisoborneol was used as the chiral auxiliary and as high as 17:1 using 3,3-(ethylenedioxy)isoborneol. The absolute stereochemistry of the major products was assigned by Mosher's method, after their conversion to the corresponding cyclohexenol. A study of the temperature dependence of the nucleophile addition to alkoxytoluene complexes revealed a thermodynamic preference for addition ortho to the ether substituent.
CERIUM(III) CHLORIDE AS CATALYTIC AND STOICHIOMETRIC PROMOTER OF THE QUANTITATIVE ADDITION OF ORGANOMETALLIC REAGENTS TO (+)-CAMPHOR AND (-)-FENCHONE
Dimitrov, Vladimir,Bratovanov, Svetoslav,Simova, Svetlana,Kostova, Kalina
, p. 6713 - 6716 (2007/10/02)
Quantitative addition of organolithium and Grignard reagents to camphor (1) and fenchone (2) proceeds via precomplexation of the ketone with CeCl3 at room temperature.Excellent addition using catalytic or substoichiometric amounts of CeCl3 is demonstrated
Highly diastereoselective additions of organocopper reagents to 2-exo-bornyl crotonates
Bergdahl, Mikael,Nilsson, Martin,Olsson, Thomas,Stern, Kaye
, p. 9691 - 9702 (2007/10/02)
Iodotrimethylsilane-activated butylcopper adds to the chiral bornyl crotonates 1-3 in high yields and with good to excellent diastereoselectivities. In the present investigation, these reactions are compared with additions of lithium butylcuprates of vari
SYNTHESIS AND RITTER REACTION OF 1,7,7-TRIMETHYL-2-PHENYLBICYCLOHEPTAN-2-EXO-OL
Kozlov, N. G.,Popova, L. A.,Vyalimyae, T. K.,Knizhnikov, V. A.,Ol'dekop, Yu. A.
, p. 702 - 705 (2007/10/02)
1,7,7-Trimethyl-2-phenylbicycloheptan-2-exo-ol is formed stereospecifically in the reaction of camphor with phenyllithium.The corresponding individual 1,7,7-trimethyl-4-phenylbicyclohept-2-yl-exo-acyl-amines were obtained as a result of the nucleophilic addition of acetonitrile, propionitrile, or methoxypropionitrile to this tertiary alcohol, which takes place in the presence of concentrated sulfuric acid.A scheme is proposed for their formation as a result of rearrangements of the intermediately formed 1,7,7-trimethylbicyclohept-2-yl cation.
THE OCTANT RULE XXIII. ANTIOCTANT EFFECTS IN γ,δ-UNSATURATED KETONES
Toan, Vien Van,Lightner, David A.
, p. 5769 - 5774 (2007/10/02)
The exo and endo α-benzyl derivatives (1 and 2. respectively) of (+)-camphor have been synthesized and are found to exert a strong influence on the circular dichroism n?* Cotton effects: 1: Δε301max -0.36 (n-heptane) and 2: Δε302max +3.22, relative to camphor: Δε304max + 1.8 (n-heptane).Evidence for electric dipole transition moment coupling in these γ,δ-unsaturated systems is found in the n?* UV: 1: ε291max 84 (n-heptane) and 2: ε285max 303, relative to camphor: ε290max 25.
SIMPLE CAMPHOR DERIVATIVES AS CHIRAL AUXILIARIES FOR ASYMMETRIC CONJUGATE ADDITION
Somfai, Peter,Tanner, David,Olsson, Thomas
, p. 5973 - 5980 (2007/10/02)
The chiral enoates, 4, readily available in two simple steps from (+)-camphor, undergo asymmetric conjugate addition with the Gilman reagent LiBu2Cu.Chemical yields are high (70-90percent) and in the case of the naphthyl-substituted enoate 4e excellent diastereoselectivity (95percent d.e.) is observed. 3-Methyl-heptan-1-ol of correspondingly high enantiomeric purity is obtained by reduction of the conjugate adduct with lithium aluminium hydride.