H-C-OR Branch

The 2-C-methylene derivatives (17) are available by condensation of 1,1-di-methoxyprop-2-en-2-yl-lithium with 2,3-O-isopropylidene-D-glyceraldehyde, with the erythro-isomcx predominating over the t/zreo-isomer (7 3). Methanolysis of (17) afforded methyl 2-deoxy-2-C-methylene-j3-D-e/ yf ro-pentopyranoside and methyl 2-deoxy-2-C-methylene-0 -L-r)i/ eo-pentopyranoside from the erythro- 

Additions of carbon nucleophiles to 3-nitro-hex-2-enopyranosides have resulted in the preparation of several 2,3-dideoxy-3-nitrohexopyranosides with 

Ganguly, P. Kabasakalian, J. Morton, O. Sarre, A. Westcott, S. Kalliney, P. Mangi-aracina, and A. Papaphilippou,/. Chem. Soc, Chem. Commun., 1980, 56. 

The enone (29) functions as a dienophile and undergoes a Diels-Alder reaction with butadiene to give the / xo-adduct (30) exclusively. The adduct was elaborated into the bicyclic lactone (31) by standard reactions. 

The fact that the ft-methylene- -butyrolactone group is present in certain terpenoid antineoplastic agents has resulted in synthetic efforts directed at analogues derived from earbohydrates, such as (32) and (33). 3i 

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