Lithiated sulfoximines aldehyde reactions

Lithiation of to form 184 was reported by the Harmata group to be the first example of a sulfoximine-stabilized vinyl carbanion. The resulting organolithium species 184 reacted with various electrophiles to supply structurally diverse benzothiazines <88TL5229>. However, the diastereoselectivity of the reactions with aldehydes was low (Scheme 48). 

The treatment of the cyclic allyl sulfoximines 14 with n-BuLi gave the corresponding lithiated allyl sulfoximines 17, which upon reaction with ClTi(OiPr)3 afforded the cyclic bis (allyl) titanium complexes 18 and equimolar amounts of Ti(OiPr)4 in practically quantitative yields [14]. The hydroxyalkylation of the cyclic complexes 18 with saturated and unsaturated aldehydes also proceeded with >98% regioselectivity and >98% diastereoselectivity at the y-position and gave the corresponding Z-onti-configured homoallyl alcohols 5 in good yields [14]. 

The treatment of the lithiated allyl sulfoximines E-15 with 1.1-1.2 equiv of ClTi(NEt2)3 at -78 to 0°C in THF or ether afforded the corresponding mono (allyl) titanium complexes E-19 in practically quantitative yields (Scheme 1.3.7) [14, 16]. Similarly the Z-configured complexes Z-19 were obtained from the Z-configured allyl sulfoximines Z-15. Reaction of the titanium complexes E-19 with aldehydes at -78 °C took place at the a-position and gave the corresponding homoallyl alcohols 6 with >98% diastereoselectivity in medium to good yields (Scheme 1.3.8) [14, 16]. 

Addition to ketones. In 1982, Johnson and Stark31 reported the condensation reactions of (+)-(S)-Af,5-dimethyl-S-phenylsulfoximine (2a) with various aldehydes and prochiral ketones. The reaction of lithiated 2a with phenyl aryl ketones (PhCOR, R=Me, Et, n-Pr, n-Bu, and c-C6Hn) gave a mixture of two diastereomeric P-hydroxy sulfoximine adducts 54 with modest diastereoselectivity. Unfortunately, the diastereoselectivities of all of these reactions were not documented. 

The reaction of lithiated 123 with benzaldehyde gave a 5.3 1 mixture of the a-adduct 124 and the y-adduct 125, while a similar reaction with pivaldehyde produced only the a-adduct 124.75 These products were formed as mixtures of diastereoisomers, but the diastereomeric ratios were not reported. In related examples, a-adducts were exclusively obtained from the reaction of lithiated N-tert-butyldiphenylsilyl81 and N-methyl83 allylic sulfoximines with aldehydes. Again, these products were mixtures of diastereoisomers. 

Lithiation of racemic N-tosyl allylic sulfoximine 126 followed by quenching the reaction at -78 °C with benzaldehyde or isobutyraldehyde gave the a-adducts 130a and 130b, respectively, as mixtures of diastereoisomers.84 Interestingly, when these reactions were performed with an excess of the aldehyde (2 molar equiv) and... 

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