108545-30-8Relevant academic research and scientific papers
Optimisation of enantioselectivity for the chiral base-mediated rearrangement of bis-protected meso-4,5-dihydroxycyclohexene oxides: Asymmetric synthesis of 4-deoxyconduritols and conduritol F
De Sousa, Simon E,O'Brien, Peter,Pilgram, Christopher D
, p. 4643 - 4654 (2007/10/03)
A strategy based on diastereoselective epoxidation of a cyclohexene followed by chiral lithium amide-mediated epoxide rearrangement has been used to synthesise an allylic alcohol building block of >95% ee. The key step is the enantioselective rearrangement of a bis-protected meso-4,5-dihydroxycyclohexene oxide. A range of protecting groups and chiral base structures were surveyed in order to find the optimum protocol for high enantioselectivity. Using a tert-butyldimethylsilyloxy protecting group and a norephedrine-derived chiral base, a 93% yield of an allylic alcohol of >95% ee was achieved. To demonstrate the synthetic utility, this allylic alcohol was subsequently transformed into 4-deoxyconduritols and (+)-conduritol F.
Catalytic One-Pot Osmylation of Cyclohexadienes: Stereochemical and Conformational Studies of the Resulting Polyols
Tschamber, Theophile,Backenstrass, Frederique,Fritz, Hans,Streith, Jacques
, p. 1052 - 1060 (2007/10/02)
Catalytic double osmylation is described for a series of cyclohexadienes in acetone/H2O in the presence of the co-oxidant N-methylmorpholine N-oxide (NMO).The formation of polyols occurred stereospecifically with cyclohexadienes 3, 7, and 11a, leading thereby to tetrols 5a, and 9a and to allo-inositol (14a), respectively.To the contrary, trans-cyclohexadiene-diol 15a gave a mixture of the stereoisomeric inositols 18a (epi), 19a (neo), and 20a (chiro).High-field NMR let to clearcut conformational analyses of the polyhydroxylated derivatives.
Hydrogen Transfer Reactions, 18. - The cis Selectivity in Dehydrogenation by Quinones
Wehage, Hubert,Heesing, Albert
, p. 2629 - 2632 (2007/10/02)
In contrast to literature results the dehydrogenation of -1,3-cyclohexadiene by o-chloranile proceeds stereoselectively.Fast 1,5-hydrogen shifts in the last pyrolytic step of the synthesis are the cause of the contrary report. Key Words: Hydrogen transfer / Aromatization / Stereoselectivity / Quinones
Preparation of Optically Active γ-Hydroxyethyl α,β-Unsaturated γ-Lactone Using an Enzymatic Procedure
Suemune, Hiroshi,Hizuka, Michiyo,Kamashita, Tomoko,Sakai, Kiyoshi
, p. 1379 - 1381 (2007/10/02)
γ-Hydroxyethyl α,β-unsaturated γ-lactone (2) is a promising intermediate for the synthesis of eldanolide and cis,cis-1,2,3-trisubstituted cyclopentane, which could be converted to 11-deoxyprostaglandins.In order to prepare optically active 2, enzymatic hy
DOMINANT cis-DIACETOXYLATION OF ALKENES WITH TELLURIUM(IV) OXIDE AND LITHIUM BROMIDE IN ACETIC ACID
Uemura, Sakae,Ohe, Kouichi,Fukuzawa, Shin-Ichi,Patil, Suresh R.,Sugita, Nobuyuki
, p. 67 - 78 (2007/10/02)
Oxidation of alkenes with tellurium(IV) oxide and lithium bromide in acetic acid affords the corresponding α,β-diacetoxyalkanes in good yields after acetylation of the primary products with acetic anhydride/pyridine.From cyclic alkenes such as cyclopentene, cyclohexene, cycloheptene, and 1,4-cyclohexadiene, the cis-diacetate is obtained as almost the sole product.In the cases of linear cis alkenes such as cis-2-octene and cis-4-octene cis-stereochemistry is also preferred (cis/trans = 87-89/13-11), while the proportion of the cis-product is decreased in the cases of the corresponding trans-alkenes (cis/trans = 56-58/44-42).Transformation of a C-Te bond to a C-OAc bond under these reaction conditions is shown unambiguously by using β-chloroalkyltellurium(IV) trichlorides (TeCl4 adducts of alkenes) and β-oxyalkyl phenyl tellurides (oxytellurenylation products of alkenes), cis-diacetates being solely formed from the trans-tellurium compounds in a cyclohexyl system.One of the possible reaction patways for the oxidation is proposed which involves the acetoxy-, hydroxy-, and/or halogeno-tellurinylation of a double bond followed by an SN2 type acetolysis of the produced C-Te bond.
