25195-85-1Relevant articles and documents
Total synthesis of formamicin
Durham, Timothy B.,Blanchard, Nicolas,Savall, Brad M.,Powell, Noel A.,Roush, William R.
, p. 9307 - 9317 (2007/10/03)
The enantioselective total synthesis of the cytotoxic plecomacrolide natural product formamicin (1) is described. Key aspects of this synthesis include the efficient transacetalation reactions of MOM ethers 28 and 38 to form the seven-membered formyl acet
Selective, catalytic carbon-carbon bond activation and functionalization promoted by late transition metal catalysts
Bart, Suzanne C.,Chirik, Paul J.
, p. 886 - 887 (2007/10/03)
The selective catalytic activation and functionalization of carbon-carbon bonds in a series of substituted cyclopropane substrates has been developed using commercially available transition metal catalysts. Catalytic hydrogenation and olefination procedures, tolerant of a range of functional groups, have been discovered. Introduction of a chelate-assisting substituent such as [PPh2] is effective in altering the kinetic selectivity and lowering the activation barrier for the catalytic processes. Copyright
Studies on the Total Synthesis of Formamicin: Synthesis of the C(1)-C(11) Fragment
Powell, Noel A.,Roush, William R.
, p. 453 - 456 (2007/10/03)
(Matrix Presented) An efficient and highly concise synthesis of 6, corresponding to the C(1)-C(11) fragment of formamicin (1), has been accomplished by a route utilizing a diastereoselective lactate aldol reaction to set the C(6) tertiary ether and the TE
Reactions of lithium hydridosilylamides with carbonyl compounds and mixtures of carbonyl compounds and chlorotrimethylsilane
Schneider, Jan,Popowski, Eckhard,Fuhrmann, Hans
, p. 663 - 672 (2007/10/03)
The lithium hydridosilylamides Me2(H)SiN(Li)R (1: R = CMe3, 2: R = SiMe3) were allowed to react either with the non-enolizable carbonyl compounds CH2=C(Me)CHO, PhCHO and Ph2CO followed by trapping with chlorotrimethylsilane (A), or with mixtures of these carbonyl compounds and chlorotrimethylsilane (B). In the second case the course of the reactions is determined by the carbonyl compound. The composition of the reaction mixtures is nearly the same according to A and B. Main products in the reactions with the aldehydes are the corresponding imines R1CH=NR R1 = CH2=C(Me), Ph) 3, 4, 8, 9 formed by addition of the hydridosilylamides to the C=O group of the aldehydes and subsequent LiOSiMe2H elimination. Partial hydrosilylation of the aldehydes by the hydridosilanolate followed by the trimethylsilylation yields the alkoxydisiloxanes R1CH2OSiMe2OSiMe3 6, 11. In some cases 2 partially reacts under hydrosilylation to give the alkoxydisilazanes R1CH2OSiMe2NHSiMe3 7, 12. The hydrosilylation is the preferred reaction of 1 and 2 with benzophenone. The compounds Ph2CHOSiMe2NHR 13, 14 are obtained. This difference in the reaction behaviour of 1 and 2 towards the aldehydes and benzophenone is mainly due to steric reasons. Depending on the conditions the imines Ph2C=NR 20, 21 may be formed. Ph2CHOSiMe2OSiMe3 (22) is a secondary product of imine formation. In all reactions of 1 and 2 with the carbonyl compounds the corresponding alkoxysilanes R1CH2OSiMe3 (5: R1 = CH2=C(Me), 6: R1 = Ph) and Ph2CHOSiMe3 (15) are generated. Compounds resulting from a reaction of 1 and 2 with chlorotrimethylsilane are produced to minor extent, but only if the molar ratio of amide to carbonyl compounds is not greater than one. The formation of a silanimine intermediate in reaction according to B is not observed.
Carbohydrates as chiral auxiliaries: Synthesis of 2-hydroxy-β-D-glucopyranosides
Charette,Marcoux,Cote
, p. 7215 - 7218 (2007/10/02)
A new 2-step, 1-pot procedure for the stereoselective glycosylation of allylic alcohols with 1,2-di-O-benzoyl-β-D-glucopyranosides to produce 2-hydroxy-β-D-glucopyranosides has been developed. The required precursor for the glycosylation was readily obtained from tri-O-benzyl-D-glucal in 2 steps (91% overall).
SYNTHESIS OF DIOSPHENOL ETHERS BY MEANS OF ALKOXYTRIMETHYLSILANES
Ponaras, A. A.,Meah, Md. Younus
, p. 4953 - 4956 (2007/10/02)
α-Diketones may be O-alkylated with a variety of alkoxytrimethylsilanes.
Ring Opening of Oxiranes by Trimethylsilyl Trifluoromethanesulfonate
Murata, Sizuaki,Suzuki, Masaaki,Noyori, Ryoji
, p. 247 - 254 (2007/10/02)
Trimethylsilyl trifluoromethanesulfonate promotes ring opening reactions of oxirane derivatives.The reaction course is highly affected by the structures and substitution pattern of the substrates.Tetra-, tri, and 2,2-disubstituted oxiranes and simple cycloalkene oxides are converted to the corresponding allylic alcohol trimethylsilyl ethers.The overall transformation is interpreted in terms of trans addition of the silyl trifluoromethanesulfonate to the oxirane ring followed by base-promoted anti elimination of a trifluoromethanesulfonic acid element. 2,3-dialkyl- or monoalkyloxiranes isomerize to the corresponding ketones and aldehydes, respectively. (Z)-Cyclooctene oxide undergoes the transannular reaction to give endo-cis-2-trimethylsiloxybicyclooctane.The reaction of 6-methyl-5-hepten-2-one oxide produces 2,2,6-trimethyl-3-trimethylsiloxy-3,4-dihydro-2H-pyran. 1,2-Methyl migration takes place in the reaction of (E)-3α-t-butyldimethylsiloxy-5α-pregnene 17α,20-oxide to afford 3α-t-butyldimethylsiloxy-17β-methyl-17α--18-nor-5α-androst-13(14)-ene. α-Pinene oxide gives trans-carveol trimethylsilyl ether.
TRIMETHYLSILYL TRIFLATE IN ORGANIC SYNTHESIS
Noyori, R.,Murata, S.,Suzuki, M.
, p. 3899 - 3910 (2007/10/02)
Trimethylsilyl triflate is a powerful silylating agent for organic compounds and acts as a catalyst which accelerates a variety of nucleophilic reactions in aprotic media.The reactions proceed via one-center, electrophilic coordination of the silyl group to hetero functional groups and exhibit unique selectivities.
