- Synthesis of alcohols from m-fluorophenylsulfones and dialkylboranes: Application to the C14-C35 building block of E7389
-
The reaction of m-fluorophenylsulfone anions with dialkylboranes, followed by alkaline hydroperoxide oxidation, yields alcohols in high yields. Optimization of the process, scope and limitation, and application to the synthesis of one of the C14-C35 building blocks of E7389, a right half analogue of halichondrin B, are reported.
- Liu, Lei,Henderson, James A.,Yamamoto, Akihiko,Bremond, Paul,Kishi, Yoshito
-
p. 2262 - 2265
(2012/06/30)
-
- A novel one-pot synthesis of secondary alcohols from esters
-
Alkylation or vinylation by using organometallic reagents after partial reduction of carboxylic esters with LDBBA gave secondary alcohols, also involving allyl alcohols, without any isolation of intermediates in good yield (54-78%).
- Chae, Min Jung,Jeon, Ah Ram,Park, Jae Kyo,An, Duk Keun
-
experimental part
p. 1718 - 1720
(2011/04/25)
-
- Construction of cyclopentyl carbinols from ω-tosyloxy-1-alkenyl boronate esters and grignard reagents
-
Addition of RMgCl (R = n-Bu, Ph) to pinacol esters of 6-tosyloxy-l-alkenyl boronic acids at -78 °C gave the borates, which upon warming to room temperature underwent migration of R on boron to C(1) carbon and concomitant ring construction C-C bond formati
- Kobayashi, Yuichi,Asano, Moriteru,Kiyotsuka, Yohei
-
scheme or table
p. 787 - 791
(2010/09/18)
-
- Pentamethylcyclopentadienide in organic synthesis: Nucleophilic addition of lithium pentamethylcyclopentadienide to carbonyl compounds and carbon-carbon bond cleavage of the adducts yielding the parent carbonyl compounds
-
Lithium pentamethylcyclopentadienide (C5Me5Li, Cp*Li) reacted with aromatic aldehyde to provide the corresponding carbinol in excellent yield. The carbinol returns to the parent aldehyde and pentamethylcyclopentadiene upon exposure to acid or due to heating. Chlorodimethylaluminum is essential as an additive to attain the nucleophilic addition of Cp*Li to aliphatic aldehyde. The carbinol derived from aliphatic aldehyde returns to the parent aldehyde and pentamethylcyclopentadiene by the action of a catalytic amount of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). The reversible addition/elimination of the Cp* group can represent a protection of aldehyde. Mechanistic details of the carbon-carbon bond cleavage are also disclosed.
- Uemura, Minoru,Yagi, Kazunari,Iwasaki, Masayuki,Nomura, Kenichi,Yorimitsu, Hideki,Oshima, Koichiro
-
p. 3523 - 3535
(2007/10/03)
-
- Chlorodimethylaluminum-promoted nucleophilic addition of lithium pentamethylcyclopentadienide to aliphatic aldehydes and DDQ-mediated carbon-carbon bond cleavage of the adducts providing the parent aldehydes
-
Treatment of aliphatic aldehyde with lithium pentamethylcyclopentadienide in the presence of chlorodimethylaluminum provided the corresponding carbinol in excellent yield. The carbinol returns to the parent aldehyde and pentamethylcyclopentadiene by the a
- Uemura, Minoru,Yorimitsu, Hideki,Oshima, Koichiro
-
p. 163 - 166
(2007/10/03)
-
- Nickel-catalyzed alkylation of aldehydes with trialkylboranes
-
(Chemical Equation Presented) Nickel-catalyzed alkylation of aldehydes with trialkylboranes proceeds smoothly in the presence of a catalytic amount of 5-allyl-1,2,3,4,5-pentamethyl-1,3-cyclopentadiene or an excess of cesium carbonate to afford the corresponding secondary alcohols.
- Hirano, Koji,Yorimitsu, Hideki,Oshima, Koichiro
-
p. 4689 - 4691
(2007/10/03)
-
- Chiral lithium amido sulfide ligands for asymmetric addition reactions of alkyllithium reagents to aldehydes
-
Six chiral amino sulfides have been synthesised from the amino acids phenylalanine, phenylglycine and valine. These amino sulfides were used as chiral ligands in the asymmetric addition of n-butyllithium and metyllithium to various aldehydes at low temperatures. The highest stereoselectivities were obtained with benzaldehyde, resulting in 1-phenyl-1-pentanol and 1-phenyl-1-ethanol in enantiomeric excesses of >98.5 and 95%, respectively. These stereoselectivities were significantly higher than those induced by the ether analogues.
- Granander, Johan,Sott, Richard,Hilmersson, Goeran
-
p. 439 - 447
(2007/10/03)
-
- Enantioselective butylation of aliphatic aldehydes by mixed chiral lithium amide/n-BuLi dimers
-
The enantioselective butylation of aliphatic aldehydes with mixtures of n-butyllithium and chiral lithium amides in a diethyl ether-dimethoxymethane solvent mixture is described. Enantiomeric excesses ranging from 91 to 98.5% were observed for several aliphatic alcohols. The asymmetric butylation of the prochiral aldehydes proceeds much faster by the mixed lithium amide/n- BuLi complexes than by tetrameric n-BuLi.
- Arvidsson, Per I.,Davidsson, Oejvind,Hilmersson, Goeran
-
p. 527 - 534
(2007/10/03)
-
- A new convenient procedure to prepare organomanganese reagents from organic halides and activated manganese
-
A new method to obtain activated manganese metal, especially attractive for large scale preparative organic chemistry, is described. The key point is the use of 2-phenylpyridine as electron carrier to reduce manganese chloride by lithium. The active manganese thus obtained was used to prepare various organomanganese reagents from organic halides. The reactivity of these reagents has been studied (acylation, 1,2- or 1,4-addition, alkylation and alkenylation).
- Cahiez, Gerard,Martin, Arnaud,Delacroix, Thomas
-
p. 6407 - 6410
(2007/10/03)
-
- The stereochemistry of the vinylogous Peterson elimination
-
Base-induced eliminations of the vinylogous β-hydroxysilanes 7, 9, 11 and 12 are stereospecifically syn, giving largely the trans,trans-diene 8 from 7 and 11, the cis,trans-diene 10 from 9, and the trans,cis-diene 13 from 12. When a cis double bond is produced, it is selectively placed adjacent to the carbon atom that originally carried the hydroxy group. E2′ Reactions with silyl as the electrofugal group and acetate as the nucleofugal group, initiated by fluoride ion, are not stereospecific, but can be highly stereoselective in favour of the trans,trans-diene 8 when the carbon substituent at the silicon-bearing end is a cyclohexyl group and the double bond is cis, and in favour of the trans,cis-diene 13 when the carbon substituent at the silicon-bearing end is a methyl group and the double bond is trans. Attempts to use the Peterson reactions to make o-quinodimethanes stereospecifically failed, with no evidence of 1,4-elimination from the alcohols 40 and 41. The corresponding E2′ reaction from the esters using fluoride ion on the acetates or formates 46 and 47 gave stereoselectively the E,E-quinodimethane 48.
- Fleming, Ian,Morgan, Ian T.,Sarkar, Achintya K.
-
p. 2749 - 2763
(2007/10/03)
-
- Selectivity in Organic Group Transfer in Reactions of Mixed Diorganomanganese(II) and Triorganomanganate(II) with 2-Cyclohexen-1-one or Cyclohexanecarbaldehyde
-
The unsymmetrical diorganomanganeses(II) (R1R2Mn) and magnesium triorganomanganates(II) (R21R2MnMgX) reacted with 2-cyclohexen-1-one to produce the 1,4-addition products in moderate to good yields. The approximate reactivity order obtained from the product distribution was CH2=CHCH2 > PhS > n-Bu > Ph > Me, Me3SiCH2, n-C6H13-CΞC. In contrast, the reactivity order for the addition of these reagents to cyclohexanecarbaldehyde was CH2=CHCH2 > Ph > Me > n-Bu > n-C6H13CΞC > Me3SiCH2.
- Yorimitsu, Hideki,Hayashi, Yasuhiro,Tang, Jun,Shinokubo, Hiroshi,Oshima, Koichiro
-
p. 2297 - 2300
(2007/10/03)
-
- A study of methyl and tert-butyl as non migrating groups in the reaction of me(organyl)zinc and t-bu(organyl)zinc with aldehydes
-
A series of mixed methyl (organyl) and tert-butyl(organyl)zincs were prepared by reaction of ZnCl2 with Grignard reagents. In the presence of salts t-butyl migrates to a lessor extent than methyl in the reaction with aldehydes. In the absence of salts both groups are comparable. BuZnMe prepared under salt-free conditions adds to benzaldehyde in 82.4% ee and in 85% yield, comparable to the reaction with distilled dibutylzinc.
- Laloe, Eric,Srebnik, Morris
-
p. 5587 - 5590
(2007/10/02)
-
- A new type of complex reagent, R4Pb / TiCl4
-
Tetraalkllleads (R4Pb) reacted quite smoothly with aldehydes R'CHO in the presence of TiCl4 to produce the corresponding alcohols (RCHOHR′) in high to good yields. The reagent system, R4Pb/ TiCl4, exhibited high chemoselectivity; only aldehydes underwent the alkylation in the presence of ketones. Further, the new reagent exhibited high 1,2- and 1,3-asymmetric induction. The transfer order of alkyl groups in the reaction of aldehydes with mixed tetraalkylleads/TiCl4 was determined; Me>Et.i-Pr?n-Bu.
- Yamamoto, Yoshinori,Yamada, Jun-Ichi,Asano, Tetsuya
-
p. 5587 - 5596
(2007/10/02)
-
- DEPROTECTION OF BENZYL TYPE PROTECTING GROUPS FOR HYDROXY FUNCTIONS BY A PHOTOINDUCED SINGLE ELECTRON TRANSFER REACTION
-
DMPM ethers were cleaved by a photo-induced single electron transfer reaction using dicyanoanthracene and anthraquinone as electron acceptors.A similar reaction occured when dimethoxynaphthylmethyl (DMNM) ethers were irradiated in the presence of dicyanob
- Nishida, Atsushi,Oishi, Satoshi,Yonemitsu, Osamu
-
p. 2266 - 2268
(2007/10/02)
-