Opening of carbohydrate 56-epoxides with chiral acetate and propionate enolate equivalents attached to the iron chiral auxiliary [(C5H5)Fe(CO)(PPh3)].
作者:Stephen G. Davies、Helen M. Kellie、Robert Polywka
DOI:10.1016/s0957-4166(00)80401-2
日期:1994.12
The lithium enolate derived from the chiral iron acetyl complex (RS)[(C5H5)Fe(CO)(PPh(3))COCH3] (RS)-1 opens, in the presence of boron trifluoride etherate, the carbohydrate 5,6-epoxides, 5,6-anhydro-3-O-benzyl-1,2-O-isopropylidene-alpha-D- allofuranose 3, 5,6-anhydro-3-O-benzyl-1,2-O-isopropylidene-beta-L- talonofuranose 4, 5,6-anhydro-3-O-benzyl-1,2-O-isopropylidene-alpha-D- glucofuranose 5, and 5,6-anhydro-3-O-benzyl- 1,2-O-isopropylidene-beta-L-idofuranose 6 to generate after decomplexation the doubly homologated gamma-lactones 3-O-benzyl-6,7-dideoxy- 1,2-O-isopropylidene-alpha-D-allo-octafuranuro-5,8-lactone 15, 3-O-benzyl-6,7-dideoxy-1,2-O-isopropylidene-beta-L-talono- octafuranurono-5,8-lactone 16, 3-O-benzyl-6,7-dideoxy-1,2-O-isopropylidene-alpha-D-gluco- octafuranuro 17, and 3-O-benzyl-6,7-dideoxy-1,2-O-isopropylidene-beta-L-ido- octafuranurono-5,8-lactone 18 respectively. The lithium enolate derived from the homochiral iron propionyl complexes (R)-[(C5H5)Fe(CO)(PPh(3))COCH2CH3] (R)-2 and (S)-[(C5H5)Fe(CO)(PPh(3))COCH3] (S)-2 convert after decomplexation 5,6-anhydro-3-O-benzyl-1,2-O-isopropylidene-alpha-D- glucofuranose 5 to 7(R)-methyl-3-O-benzyl-6,7-dideoxy-1,2-O octafuranurono-5,8-lactone 20 and 7(S)-methyl-3-O-benzyl-6,7-dideoxy-1,2- O-isoprapylidene-alpha-D-gluco-octafuranurono-5,8-lactone 22 respectively.