Expeditious route to F unit building block of moenomycin A

Synthesis of the versatile F sugar unit building block of moenomycin A, Phe nyl 2-O-levulinoyl-4-C-methyl-1-thio-beta-D-glucopyranosiduronic acid is de scribed starting from phenyl 1-thio-beta-D-galactopyranoside. The key synth etic steps included: (I) Regioselective protection of the 3-OH group of phe nyl 6-O-trityl-1-thio-beta-D-galactopyranoside as its TBDMS ether, (ii) TBA F mediated TBDMS group migration from the C-3 to C-2 position of phenyl 3-O -TBDMS-4-C-methyl-6-O-trityl-1-thio-beta-D-galactopyranoside, and (iii) Sel ective deprotection of TBDMS and trityl groups in phenyl 2-O-levulinoyl-3-O -TBDMS-4-C-methyl-6-O-trityl-1 -thio-beta-D-glucopyranoside by DDQ. (C) 199 8 Elsevier Science Ltd. All rights reserved.