123072-84-4Relevant articles and documents
Mechanistic insights from ab initio calculations on a nitrogen analogue of the boron-mediated aldol reaction
Bernardi, Anna,Gennari, Cesare,Goodman, Jonathan M.,Leue, Volker,Paterson, Ian
, p. 4853 - 4866 (1995)
Molecular orbital calculations were used to study a nitrogen analogue of the boron mediated aldol reaction. Experimental results show that high selectivity can be obtained in some cases, at the cost of low yields. The molecular orbital calculations are us
ENANTIO- AND DIASTEREOSELECTIVE ALDOL REACTIONS OF ACHIRAL ETHYL AND METHYL KETONES WITH ALDEHYDES: THE USE OF ENOL DIISOPINOCAMPHEYLBORINATES.
Paterson, Ian,Goodman, Jonathan M.,Lister, M. Anne,Schumann, Russell C.,McClure, Cynthia K.,Norcross, Roger D.
, p. 4663 - 4684 (2007/10/02)
Enol diisopinocampheylborinates, derived from achiral ethyl and methyl ketones by enolisation in the presence of tertiary amine bases (iPr2NEt or Et2N), undergo enantio- and diastereoselective aldol reactions with aldehydes.The reagents employed, (+)- and (-)-(Ipc)2BOTf, are easily prepared in enantiomerically pure form in two steps from (-)- and (+)-α-pinene, respectively.The aldol reaction between ethyl ketones and aldehydes using (+)- or (-)-(Ipc)2BOTf/iPr2NEt in dichloromethane gives, via the derived chiral Z-enol borinates, syn-α-methyl-β-hydroxy ketones in good enantiomeric excess (66-93percent ee) and with high diastereoselectivity (>95percent).In contrast, the anti-selective aldol reaction of diethylketone via the isomeric E-enol diisopinocampheylborinate (by enolisation with (-)-(Ipc)2BCl) with methacrolein proceeds with negligible enantioselectivity.Use of both the triflate and chloride reagents in the aldol reaction of methyl ketones with aldehydes gives β-hydroxy ketones in moderate enantiomeric excess (53-78percent ee) with a reversal in the enantioface selectivity of the aldehyde compared to the corresponding ethyl ketone syn aldol.This variable selectivity is interpreted as evidence for the participation of competing chair and boat transition states.Other chiral dialkylboron triflate reagents investigated led to reduced enantioselectivities in diethylketone-aldehyde aldol reactions.
ALDOL REACTIONS OF METHYLKETONES USING CHIRAL BORON REAGENTS: A REVERSAL IN ALDEHYDE ENANTIOFACE SELECTIVITY
Paterson, Ian,Goodman, Jonathan M.
, p. 997 - 1000 (2007/10/02)
The enantioselectivity of aldol additions of methylketones to aldehydes using(-)-(Ipc)2BOTf, (-)-1, and Pri2NEt is generally lower(53-78percent ee) than that for the corresponding ethylketone reaction and occurs with the opposite sense of aldeh
