- Method For Manufacturing Hydroxyl Group-containing Acetal Compound
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A method for manufacturing an acetal compound represented by the formula [1] in which the steps (A) to (D) as defined herein are performed sequentially, and an acetal compound of the formula [1] which is produced by the method: wherein n is 0 or 1 provided that R1 groups may be bonded or may not be bonded to each other when n is 0; R1 is an alkyl group having 1 or 2 carbon atoms or an alkylene group having 1 or 2 carbon atoms and the R1 groups may be same or different from each other; and R2 is an alkylene group having 1 or 6 carbon atoms.
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Page/Page column 5
(2012/11/08)
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- Asymmetric synthesis of D- and L-2-deoxy-4-thioriboses
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Both D- and L-enantiomers of 2-deoxy-4-thioribose derivatives 12 and 17 were prepared stereospecifically in 12 steps from 1,3-propanediol. The key intermediary 2,3-epoxy alcohols, 8 and 15 were obtained with high enantiomeric excess by the Sharpless asymmetric epoxidation using (+)-L- diethyl tartrate and (-)-D-diethyl tartrate.
- Uenishi,Motoyama,Takahashi
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p. 101 - 110
(2007/10/02)
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- TOTAL SYNTHESIS OF MAYTANSINOIDS. APPROACH TO 4,6-BISDEMETHYLMAYTANSINE AND 4-DEMETHYLMAYTANSINE
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A convergent strategy was elaborated to synthesize maytansine 1 and maytansinoids modified on the carbon skeleton, especially 4-demethylmaytansine 2, 6-demethylmaytansine 3, 4,6-bisdemethylmaytansine 4.In this paper, the feasibility of the project was verified by the preparation of key intermediates for the synthesis of 4,6-bisdemethylmaytansine and 6-demethylmaytansine.The C-1-N open chain compound 18 in the 4,6-bisdemethyl series was obtained.
- Benechie, Michel,Delpech, Bernard,Khuong-Huu, Qui,Khuong-Huu, Francoise
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p. 1895 - 1910
(2007/10/02)
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- Stereocontrolled Preparation of Cyclic Xanthate; a Novel Synthetic Route to 4-Thiofuranose and 4'-Thionucleoside
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Optically active cyclic xanthate was prepared by the reaction of an epoxy alcohol with NaH and CS2, and was found to be a useful intermediate for synthesis of 4-thio-2-deoxyribose and 4'-thio-2'-deoxyribonucleoside.
- Uenishi, Jun'ichi,Motoyama, Mitsuhiro,Nishiyama, Yoshitaka,Wakabayashi, Shoji
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p. 1421 - 1422
(2007/10/02)
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- Thiazolidinylethylchlorocarbonates
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This invention relates to 2-(thiazolidin-2'-yl) ethylchlorocarbonates useful as intermediates in the synthesis of photographic image dye-providing materials and to their preparation by the reaction of the appropriate 2-(2'-hydroxyethyl)-thiazolidine with phosgene under certain conditions.
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- Hydroboration. 57. Hydroboration with 9-Borabicyclononane of Alkenes Containing Representative Functional Groups
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The hydroboration of alkenes containing representative functional groups was examined with 9-borabicyclononane (9-BBN) in order to extend the hydroboration reaction for the preparation of functionally substituted organoboranes.Terminal alkenes containing a remote functional group are hydroborated with a remarkable regioselectivity (>=98percent terminal), producing the corresponding stable organoboranes. 9-BBN hydroborates the allylic derivatives so as to place boron essentially on the terminal carbon atom (>=97percent).The directive effect is further enhanced (>=99percent) in the case of β-methylallyl derivatives.The hydroboration of crotyl derivatives attaches boron predominantly at the 2-position, followed by an elimination-rehydroboration sequence.However, crotyl alcohol can be protected against elimination as the tert-butyl or tetrahydropyranyl ethers.The hydroboration-oxidation of ethyl crotonate involves a series of elimination, hydroboration, and condensation processes.In the vinyl, crotyl, and isobutenyl systems, the mesomeric effect of the substituent favors the placement of boron at the β-position, while the inductive effect favors the α-position, with the former effect predominating in most cases.Acyclic β-substituted organoboranes undergo rapid elimination.Nonpolar solvents and lower reaction temperatures decrease the rate of elimination.However, those derived from cyclic vinyl derivatives are relatively stable under neutral conditions, undergoing facile elimination in the presence of a base.
- Brown, Herbert C.,Chen, Jackson C.
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p. 3978 - 3988
(2007/10/02)
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