65989-90-4Relevant academic research and scientific papers
3,3-Diethoxypropyl-lithium: A Masked Lithium Propanal Homoenolate in Organic Synthesis
Barluenga, Jose,Fernandez, Jose R.,Rubiera, Covadonga,Yus, Miguel
, p. 3113 - 3118 (2007/10/02)
3,3-Diethoxypropyl-lithium is prepared by lithiation of the corresponding chlorinated precursor with lithium naphthalenide at -78 deg C; the reaction of this masked propanal homoenolate with different elctrophilic reagents CO, (CH2)7CO, PhCOMe, PhCH=NPh, PhCONEt2, PhCN, c-C6H11CN, 4-MeC6H4CN> leads to the corresponding mono- and bi-functionalized compounds.In the case of the reaction with aldehydes or ketones the prepared crude products are oxidized with m-chloroperbenzoic acid, yielding directly the γ-substituted butyrolactones.
d1- and d3-Selective Reactions of Sulfur-substituted Allylic Titanium Derivatives with Aldehydes and Ketones
Widler, Leo,Weber, Theodor,Seebach, Dieter
, p. 1329 - 1344 (2007/10/02)
As previously reported, double deprotonation of allylmercaptane with butyllithium produces the moderately to poorly d3-selective dilithium derivative 1a of thioacrolein (or 1-thiabutadiene).Addition of an equimolar amount of chlorotriisopropoxytitanium generates a reagent 1c, which combines with aldehydes and ketones almost exclusively in the γ-position (d3-reactivity, products 2, Table 1, 18 examples).The 2-methyl analogue 4b exhibits a similar d3-selectivity, with somewhat lower chemical yields (products 5, Table 2, 7 examples).In contrast to the dianion deri vatives, methyl- and phenyl-allyllithium combine with chlorotriisopropoxytitanium to give reagents (6a, 6b) which add to the same electrophiles practically only in the α-RS-position (d1-reactivity, products 7 and 8, Table 3, 12 examples).Possible conversions of the selectively produced α- and γ-adducts to vinyloxiranes, to γ-hydroxy- and to ε-keto aldehyde derivatives are discussed (Scheme 1).Some examples of Hg(II)-assisted alcoholyses (CH3OH, C2H5OH) of γ-adducts 2 to 2-alkoxytetrahydrofurans (9, 10) are described (Scheme 2, Table 4). "Titanation" of the Li derivatives not only causes high regioselectivity, but also excellent chemical selectivity of the nucleophilic reagents: they preferentially add to aldehydes vs. ketones and are compatible with other functional groups, such as CN, NO2, I, in the substrate.
