Lead-Mediated Highly Diastereoselective Allylation of Aldehydes with Cyclic Allylic Halides
Lead was found to efficiently mediate the allylation reactions of carbonyl compounds with cyclic allylic halides in the presence of stoichiometric amounts of lithium chloride and a catalytic amount of GaCl3 (20 mol %), leading to the desired homoallylic alcohols in modest to high yields with excellent diastereocontrol (>99:1 syn/anti) and good functional group tolerance. In contrast, the use of either 2-pyridinecarboxaldehyde as the carbonyl substrate or (E)-cinnamyl bromide as the allylating agent produced the corresponding product with reversed diastereoselectivity (>99:1 anti/syn).
An efficient Bi/NH4I-mediated addition reaction for the highly diastereoselective synthesis of homoallylic alcohols in aqueous media
An efficient water-based bismuth-mediated addition reaction of carbonyl compound with cyclic allylic halide was developed. The reactions proceeded smoothly in aqueous DMF in the presence of ammonium iodide to afford the corresponding syn-homoallylic alcohols in moderate to good yields with excellent diastereoselectivities (>99:1 syn:anti). Reversal of product diastereoselectivity was observed when heteroaryl aldehyde possessing an adjacent chelating nitrogen atom was employed as substrate.
A nickel catalyst for the allylboration of aldehydes is reported, facilitating the preparation of homoallylic alcohols in high diastereoselectivity. The observed diastereoselectivities and NMR experiments suggest that allylation occurs through a well-defined six-membered transition state, with nickel acting as a Lewis acid.
Dennis, Francesca M.,Partridge, Benjamin M.,Robertson, Craig C.
p. 1903 - 1914
(2020/07/04)
Method for preparing high allyl alcohol compound
The invention relates to a method for preparing a high allyl alcohol compound. An effective metal-mediated highly diastereoselective allylation reaction of a carbonyl compound with allyl halide is mainly provided, a corresponding high allyl alcohol is obt
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Paragraph 0065; 0066; 0067; 0118; 0119; 0120
(2019/05/04)
Bismuth-Mediated Diastereoselective Allylation Reaction of Carbonyl Compounds with Cyclic Allylic Halides or Cinnamyl Halide
An efficient diastereoselective allylation of various carbonyl compounds with cyclic allylic halides by using commercially available bismuth powder in the presence of LiI was developed. Among all the metals screened, bismuth was found to be the best mediator for the transformation. The reactions involving various cyclic allylic halides proceeded smoothly at room temperature to produce the desired homoallylic alcohols in good to excellent yields with high diastereoselectivities (>99:1 dr). Reversed diastereoselectivity was obtained when carbonyl substrate (e. g., 2-pyridinecarboxaldehyde, glyoxylic acid) containing chelating substituent was used in the allylation reaction. In addition, the reactions involving acyclic (E)-cinnamyl bromide as substrate worked equally well with high diastereocontrol. (Figure presented.).
DIASTEREOSELECTIVITY, DIASTEREOFACIAL SELECTIVITY AND REGIOSELECTIVITY IN THE REACTIONS OF CYNNAMYL CHLORIDE WITH ALDEHYDES MEDIATED BY TIN AND ALUMINIUM
The reaction of cinnamyl chlorie with a series of aryl and alkyl aldehydes mediated by tin and aluminium has been shown to be regioselective and threo diastereoselective.For aldehydes with chirality adjacent to the carbonyl function some diastereofacial s
Coxon, James M.,Eyk, Stephen J. van,Steel, Peter J.
p. 1029 - 1042
(2007/10/02)
HIGHLY DIASTEREOSELECTIVE REACTIONS OF (E)-CINNAMYL CHLORIDE WITH ALDEHYDES MEDIATED BY TIN AND ALUMINIUM
The reactions of (E)-cinnamyl chloride with aldehydes in H2O:THF:HBr in the presence of tin and aluminium powders proceed with very high stereoselectivity.
Coxon, James M.,Eyk, Stephen J. van,Steel, Peter J.
p. 6121 - 6124
(2007/10/02)
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