- A novel stereoselective synthesis of (-)-β-conhydrine from (R)-2,3-O-cyclohexylidine glyceraldehyde
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A novel stereoselective synthesis of (-)-β-conhydrine is achieved. Stereoselective Grignard reaction of (R)-2,3-O-cyclohexylidine glyceraldehyde with ethyl magnesium bromide, chelation controlled stereoselective Grignard reaction of allyl imine derivative
- Venkataiah, Mallam,Fadnavis, Nitin W.
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experimental part
p. 6950 - 6952
(2009/12/09)
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- Stereoselective synthesis of (3R,4S,5S,9S)-3,5,9-trihydroxy-4-methylundecanoic acid δ-lactone
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A stereoselective synthesis of the pentaketide lactone (3R,4S,5S,9S)-3,5,9-trihydroxy-4-methylundecanoic acid δ-lactone has been achieved.
- Yadav,Reddy, P. Murali Krishna,Reddy, P. Venkatram
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p. 1037 - 1039
(2008/02/05)
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- Convergent approach to pumiliotoxin alkaloids. Asymmetric total synthesis of (+)-pumiliotoxins A, B, and 225F
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A versatile convergent approach for preparing the pumiliotoxin alkaloids has been developed employing Pd(0)-catalyzed cross-coupling reactions between homoallylic organozincs and vinyl iodides. The (Z)-iodoalkylidene indolizidine 34, which served as a common key intermediate, was synthesized through highly stereoselective addition of the chiral silylallene 19 to (S)-acetylpyrrolidine followed by a palladium-catalyzed intramolecular carbonylation-cyclization sequence. This synthetic process allowed the first total synthesis of (+)-pumiliotoxin 225F. The intermediate (Z)-iodoalkylidene indolizidine 34 obtained was converted to a homoallylzinc chloride derivative and subjected to homoallyl-vinyl cross-coupling with the (E)-vinyl iodide 42 using Pd(PPh3)4 catalyst to give the cross-coupled product 47 with a 1,5-diene side chain. Subsequent deprotection provided (+)-pumiliotoxin A. On the other hand, the (Z)-iodoalkylidene indolizidine 34 was transformed into the homoallyl-tert-butyl zinc derivative, which underwent palladium-catalyzed cross-coupling with the (E)-vinyl iodide 50 and subsequent deprotection to afford (+)-pumiliotoxin B.
- Aoyagi, Sakae,Hirashima, Shintaro,Saito, Kosuke,Kibayashi, Chihiro
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p. 5517 - 5526
(2007/10/03)
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- Stereoselective total synthesis of lysocellin, the representative polyether antibiotic of the lysocellin family. Part 1. Synthesis of C1-C9 and C16-C23 subunits
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The C1-C9 (4) and C16-C23 subunits (9) of lysocellin (1), a representative polyether antibiotic, were synthesized stereoselectively from D-glucose and D-mannitol. Stereocontrolled hydroboration, Michael reaction, Grignard reaction, etc. were successfully
- Horita, Kiyoshi,Inoue, Takayuki,Tanaka, Kazuhiro,Yonemitsu, Osamu
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p. 531 - 550
(2007/10/03)
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- Diastereo- and enantioselective synthesis of 1,2-amino alcohols and protected α-hydroxy aldehydes from glycol aldehyde hydrazones
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Starting from chiral glycol aldehyde hydrazones (S)-2, we prepared differently protected α-hydroxy aldehydes (R)- or (S)-4 as well as N-acetyl-protected 1,2-amino alcohols (R)-11 in high enantiomeric excesses via azaenolate α-alkylation or nucleophilic 1,2-addition to the CN double bond. The successive introduction of two vicinal stereogenic centres opens a new, flexible syn-diastereo- and enantioselective route to functionalised, N-acetyl-protected, vicinal amino alcohols (R,R)-13, which was demonstrated in the case of the γ-amino-β-hydroxycarboxylic acid statin (R,R)-15 and its analogues B. VCH Verlagsgesellschaft mbH, 1996.
- Enders, Dieter,Reinhold, Ulrich
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- Chelation-Controlled Facially Selective Cyclocondensation Reactions of Chiral Alkoxy Aldehydes: Syntheses of a Mouse Androgen and of a Carbon-Linked Disaccharide
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Magnesium bromide in tetrahydrofuran catalyzes the cycloaddition of a variety of chiral alkoxy aldehydes with activated butadienes.The stereochemistry of these products is such that they can be rationalized as arising from a reacting conformer in which th
- Danishefsky, Samuel J.,Pearson, William H.,Harvey, Daniel F.,Maring, Clarence J.,Springer, James P.
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p. 1256 - 1268
(2007/10/02)
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- ON THE STERIC COURSE OF ADDITION OF GRIGNARD REAGENTS ONTO α,β-DIALKOXY ERYTHRO AND THREO CHIRAL ALDEHYDES. SYNTHESIS OF (+) AND (-)-EXO AND ENDO-BREVICOMIN
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Addition of BrMgCH2CH3 onto the erythro and threo aldehydes (1) and (2) to form (3)+(6) and (9)+(10) proceeds with 6:4 and 8:2 threo-erythro selectivity, respectively.From (3) and (6), (2S) and (2R)-2-benzyloxy butyraldehyde (13) and (14) have been prepared.Addition of ClMgCH2CH2CH2(COCH2CH2O)CH3 onto (13) and (14) proceeds with 6:4, threo-erythro selectivity, to give after preparative gas chromatographic separation, the enantiomeric forms of exo- and endo-brevicomin (19), (21) and (20), (22).
- Bernardi, Rosanna,Fuganti, Claudio,Grasselli, Piero
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p. 4021 - 4024
(2007/10/02)
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