129320-32-7Relevant articles and documents
Application of stereocontrolled aldol coupling to synthesis of segments of immunosuppressants FK-506 and rapamycin
White, James D.,Deerberg, J?rg,Toske, Steven G.,Yakura, Takayuki
supporting information; scheme or table, p. 6635 - 6641 (2011/02/26)
The sector comprising C24-C34 of FK-506 containing five of the stereogenic centers in this macrolide was synthesized from (-)-quinic acid. Aldol coupling of the C24-C34 unit with a methyl ketone representing C20-C23 of FK-506 proceeded with complete Felkin stereoselectivity to afford the C20-C34 portion of the immunosuppressant. A chelate transition state invoking coordination of a lithium enolate with a trityl ether is proposed to explain this stereoselectivity. The strategy adopted for construction of the C26-C34 moiety of FK-506 was extended to the C34-C42 subunit of rapamycin. A Mukaiyama asymmetric anti-aldol coupling was used to set in place the vicinal diol functionality at C27,28 in the C26-C33 segment of this macrolide.
Asymmetric total synthesis of Taxol
Mukaiyama, Teruaki,Shiina, Isamu,Iwadare, Hayato,Saitoh, Masahiro,Nishimura, Toshihiro,Ohkawa, Naoto,Sakoh, Hiroki,Nishimura, Koji,Tani, Yu-Ichirou,Hasegawa, Masatoshi,Yamada, Koji,Saitoh, Katsuyuki
, p. 121 - 161 (2007/10/03)
The asymmetric total synthesis of Taxol was achieved by way of B to BC to ABC to ABCD ring construction. Optically active 8-membered ring enones 1 and 2 corresponding to the B ring of Taxol have been synthesized in high yields from the linear precursors 28 and 32, respectively, by intramolecular aldol cyclization using SmI2. The optically active linear polyoxy compounds 28 and 32 were obtained by way of diastereoselective aldol reaction between aldehyde 4 and ketene silyl acetal 8 catalyzed by MgBr2 · OEt2. The chiral pentanal 4 was synthesized either by asymmetric aldol reaction of achiral aldehyde 7 and ketene silyl acetal 8 by means of a chiral Lewis acid or by diastereoselective aldol reaction between the chiral aldehyde 16, derived from L-serine, and the lithium enolate derived from methyl isobutyrate. Optically active bicyclo[6.4.0]dodecanone 38β, corresponding to the BC ring system of Taxol, was prepared from 8-membered ring enone 2 in high yield by stereoselective Michael addition and successive intramolecular aldol cyclization. Furthermore, baccatin III, the ABCD ring system of Taxol, was efficiently synthesized from the BC ring system 38β by successive construction of the A and D rings by intramolecular pinacol coupling cyclization, introduction of the C-13 hydroxyl group and an oxetane-forming reaction. Finally, the total synthesis of Taxol was accomplished by dehydration condensation between a protected N-benzoylphenylisoserine 70 or 75 and 7-TES baccatin III, prepared from baccatin III. Taxol side chains 70, 73, 75, and 77, optically active protected N-benzoylphenylisoserines, were synthesized by enantioselective aldol reaction from two achiral starting materials, benzaldehyde and an enol silyl ether 65 derived from S-ethyl benzyloxyethanethioate.
Diastereo- and Enantioselective Synthesis of syn- and anti-1,2-Diol Units by Asymmetric Aldol Reactions
Mukaiyama, Teruaki,Shiina, Isamu,Uchiro, Hiromi,Kobayashi, Shu
, p. 1708 - 1716 (2007/10/02)
syn- and anti-1,2-Diol units were prepared by using asymmetric aldol reactions of the silyl enol ethers derived from α-alkoxythioacetic S-esters with aldehydes.In the presence of tin(II) triflate, a chiral diamine, and dibutyltin diacetate, (Z)-2-benzyloxy-1-ethylthino-1-(trimethylsiloxy)ethene reacted with aldehydes to afford the corresponding anti-aldol adducts in high yields with excellent diastereo- and enantioselectivities, while syn-adducts were obtained from (Z)-2-(t-butyldimethylsiloxy)-1-ethylthio-1-(trimethylsiloxy)ethene and aldehydes under the same reaction conditions.Thus, both diastereomers can be synthesized in excellent enantiomeric excesses by simply choosing the protective groups of the alkoxyl parts of the silyl enol ethers.
Enantioselective synthesis of both diastereomers including the α-alkoxy-β-hydroxy-β-methyl(phenyl) units, by chiral tin(II) Lewis acid-mediated asymmetric aldol reactions
Kobayashi,Horibe,Saito
, p. 9629 - 9642 (2007/10/02)
Diastereo- and enantioselective synthesis of both diasteromers, including the α-alkoxy-β-hydroxy-β-methyl(phenyl) units, was performed by using chiral tin(II) Lewis acid-mediated asymmetric aldol reactions of α-alkoxy silyl enol ethers with α-ketoesters. (S)-1-Propyl-2-[(1,2,3,4-tetrahydroisoquinolinyl))methyl]pyrrolidine (13), a new type of chiral diamine, was found to be effective as a chiral source in these reactions and also in the reactions of 2-(t-butyldimethylsiloxy)-1-ethylthio-1-(trimethylsiloxy)ethene (9) with aldehydes for the synthesis of optically active syn-α,β-dihydroxy thioester derivatives. (-)-2-C-Methyl-D-erythrono-1,4-lactone and (+)-2-C-methyl-L-threono-1,4-lactone were synthesized by using these reactions.
Facile Synthesis of Optically Active anti-α,β-Dihydroxy Ester Derivatives
Mukaiyama, Teruaki,Uchiro, Hiromi,Shiina, Isamu,Kobayashi, Shu
, p. 1019 - 1022 (2007/10/02)
Anti-α,β-dihydroxy thioesters are prepared with excellent enantioselectivities by the asymmetric aldol reaction between both achiral aldehydes and silyl enol ethers derived from α-benzyloxy thioesters in the presence of a chiral promoter consisted of chir
