Reaction of derivatives of methyl 2,3-O-benzylidene-6-deoxy-alpha-L-mannopyranoside with butyllithium: synthesis of methyl 2,6-dideoxy-4-O-methyl-alpha-L-erythro-hexopyranosid-3-ulose.

Article abstract of DOI:10.1016/S0008-6215(00)83147-X

Methyl 2,3-O-benzylidene-6-deoxy-alpha-L-mannopyranoside (2) reacted with butyllithium to give a mixture of 1,5-anhydro-3-C-butyl-1,2,6-trideoxy-L-ribo-hex-1-enitol (3) and its L-arabino analogue (4), together with methyl 2,3,6-trideoxy-alpha-L-erythro-hex-2-enopyranoside (5). In contrast, the 4-O-methyl-analogue (8) of 2 was converted by butyllithium into methyl 2,6-dideoxy-4-O-methyl-alpha-L-erythro-hexo-pyranosid-3-ulose (9), which was further characterized as its oxime 10. The 4-O-benzyl analogue of 8, obtained as two separate diastereoisomers (6 and 7) differing in configuration at C-2 of the dioxolane ring gave a complex misture of products on treatment with butyllithium.