220263-61-6Relevant academic research and scientific papers
Reversal of diastereofacial selectivity in hydride reductions of N-tert-butanesulfinyl imines
Colyer, John T.,Andersen, Neil G.,Tedrow, Jason S.,Soukup, Troy S.,Faul, Margaret M.
, p. 6859 - 6862 (2007/10/03)
A variety of N-tert-butanesulfinyl imines were reduced with NaBH 4 in THF containing 2% water to provide the corresponding secondary sulfinamides in high yield and diastereoselectivity. By using the same sulfinyl imine starting materials and changing the reductant to L-Selectride, the stereoselectivity could be efficiently reversed to afford the opposite product diastereomer in high yield and selectivity.
Synthesis of enantiomerically pure N-tert-butanesulfinyl imines (tert- butanesulfinimines) by the direct condensation of tert-butanesulfinamide with aldehydes and ketones
Liu,Cogan,Owens,Tang,Ellman
, p. 1278 - 1284 (2007/10/03)
Experimental details for the first general methods for the one-step preparation of N-tert-butanesulfinyl imines (tert-butanesulfinimines) (2) from aldehydes and ketones is described. To effect the condensations of tert- butanesulfinamide (1) with aldehydes, the Lewis acidic dehydrating agents MgSO4, CuSO4, or Ti(OEt)4 are employed. Aldehyde condensations mediated by MgSO4 proceed in high yields (84-96%) when an excess of aldehyde is used. In contrast, only a slight excess of aldehyde (1.1 equiv) relative to tert- butanesulfinamide provides sulfinimines in high yields when the more Lewis acidic dehydrating agent CuSO4 is used. The CuSO4-mediated procedure is effective for a wide range of aldehydes, including sterically demanding aldehydes, such as isobutyraldehyde (90%), and electron-rich aldehydes, such as p-anisaldehyde (81%). The still more Lewis acidic Ti(OEt)4 and TI(O-i- Pr)4 also afford N-tert-butanesulfinyl aldimines from especially unreactive aldehydes, such as pivaldehyde (82%). In addition, Ti(OEt)4 is effective for the condensation of 1 with ketones to afford a wide range of N-tert- butanesulfinyl ketimines in good yields (77-91%). For sulfinyl ketimines derived from methyl or n-alkyl phenyl ketones and methyl or n-alkyl isopropyl ketones, only the E isomer is detected by 1H and 13C NMR in CDCl3. For those cases where the difference in steric demand about the imine is very small, such as for 2-hexanone, high E/Z ratios are still observed (5:1).
