97203-22-0Relevant articles and documents
Additions of Organomagnesium Halides to α-Alkoxy Ketones: Revision of the Chelation-Control Model
Read, Jacquelyne A.,Yang, Yingying,Woerpel
, p. 3346 - 3349 (2017/07/13)
The chelation-control model explains the high diastereoselectivity obtained in additions of organometallic nucleophiles to α-alkoxy ketones but fails for reactions of allylmagnesium halides. Low diastereoselectivity in ethereal solvents results from no chelation-induced rate acceleration. Additions of allylmagnesium bromide to carbonyl compounds are diastereoselective using CH2Cl2 as the solvent even though rate acceleration is still absent. Stereoselectivity likely arises from the predominance of the chelated form in solution. Therefore, a revised chelation-control model is proposed.
Stereoselective titanium-mediated aldol reactions of α-benzyloxy methyl ketones
Pellicena, Miquel,Solsona, Joan G.,Romea, Pedro,Urpi, Felix
, p. 10338 - 10350,13 (2012/12/12)
Good levels of 1,4-anti asymmetric induction are obtained in the TiCl 3(i-PrO)-mediated aldol reaction of chiral α-benzyloxy methyl ketones with a wide array of aldehydes. This methodology represents a new approach to substrate-controlled acetate aldol reactions capable of providing highly functionalized fragments in a straightforward manner, which may be useful in the design of more efficient syntheses.
The chemistry of trichlorosilyl enolates. Aldol addition reactions of methyl ketones
Denmark,Stavenger
, p. 8837 - 8847 (2007/10/03)
Investigations on the aldol addition chemistry of trichlorosilyl enolates derived from methyl ketones are presented in full. These trichlorosilyl enolates are competent aldol reagents in the absence of additives, reacting with aldehydes at ambient temperature to provide high yields of aldol adducts. When either enol or aldehyde partner bears a stereogenic center, low diastereoselectivity is observed in this uncatalyzed aldol process. The aldol additions are dramatically accelerated by the addition of catalytic quantities of chiral phosphoramides, particularly one derived from N,N'-dimethylstilbene-1,2-diamine. In this catalyzed mode, good to high enantioselectivities are obtained with a variety of achiral trichlorosilyl enolates and aldehydes. When either partner bears a stereogenic center, high diastereoselectivities are obtained with one enantiomer of the catalyst (matched case), while the other enantiomer provides low diastereoselectivity (mismatched case). The reaction scope, optimization of conditions, and stereoselection events are also discussed.
