Imines ketones

Keywords Alcohols Alkenes Asymmetric transfer hydrogenation C-alkylation Imines Ketones W-aUcylation Oxidation Reduction Transfer hydrogenation... 

En/HB(OR)2 -I- Li —Ar C12CH-0R/H202] 2-Methyl-l-oxo-l-phenyl- E21a, 985 (Imin - Keton)... 

H,6H-l,3,5-Oxathiazin 4-(4-Chlor-phenyl)-2,2.6,6-tetrakis-[trifluormethyl]-El 1, 1614/E14a/ 2, 754 (R-CS-NH2 + Keton) El4b, 280 (N —Acyl—imin + Keton)... 

Table 22. TiCh-mediated preparation of imines. Ketone Amine...

The literature describes mainly reductions in aqueous media using electrodes with high hydrogen overvoltage (mercury pool cathode, lead, graphite). In this review, we chiefly describe the possibility of hydrogenation of derivatives bearing nitro, nitroso, azo, and azoxy functions, as well as oximes and imines, ketones, and aldehydes. 

The Grignard reagents of (chloroaIkyl)(isopropo3gr)dimethylsilane (42, R -O-iPr) and (chloroalkyl)(dimethyl)phenylsilane (43, R = Ph) provide excellent hydroxyallqrl anion equivalents, which react with electrophiles such as aldehydes, imines, ] ketones and epoxides to give the adducts 44 and 45, respectively (Scheme 14). The hydroxyalkyl group 46 is revealed using the standard silyl-to-hydroxy protocols. 

An interesting extension of this method involves the reaction of Af-silyl oxyketene imines derived from cyanohydrins (Scheme 19) [81]. By judicious selection of the protecting group on the oxygen, highly functionalized (3-hydroxy cyanohydrins can be accessed with high levels of enantio- and diastereoselectivity. These products can then be transformed into a diversity of structural motifs (amines, aldehydes, imines, ketones) important for the synthesis of polyketide and other classes of natural products. In addition, the ethers can be easily converted to enantiomerically enriched unsymmetrical benzoins, thus revealing the synthetic equivalency of A-silyl oxyketene imines as acyl anions (Scheme 19). 

Keywords Aldehydes Alkenes Imines Ketones Phosphorus... 

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