chapter  29
8 Pages

Isopropyl 2,3,4,6-Tetra-O-benzoyl-1-thio-β-d- galactopyranoside, a Convenient Galactosyl Donor

Experimental Methods ........................................................................................... 229 General Methods ............................................................................................... 229

Isopropyl 2,3,4,6-Tetra-O-benzoyl-1-thio-β-d-galactopyranoside (2) ......... 229 Methyl 2,3,4,6-Tetra-O-benzoyl-β-d-galactopyranosyl-(1→6)-2,3,4-triO-benzyl-α-d-glucopyranoside (4) ...............................................................230

Acknowledgment ................................................................................................... 231 References ..............................................................................................................234

side (IPTG), as the compound is often referred to by commercial suppliers of carbohydrate derivatives, is known more to molecular biologists than to carbohydrate chemists. IPTG is a molecular biology reagent, largely because of its ability to induce expression of genes under the control of the lac operon.2 Carbohydrate chemists are more familiar with other alkyl and aryl 1-thioglycosides and use them, in their fully protected form, as glycosyl donors in carbohydrate synthesis. Their popularity lies in their versatility in glycosylation reactions combined with long shelf life. Unfortunately, due to the odorous nature of most thiols, preparation of many useful 1-thioglycosides is neither a pleasant nor a desirable task in an academic laboratory, the latter due to health and environmental concerns. IPTG has been available commercially for many years, but at pricing that made the routine use of the compound as a synthetic intermediate cost prohibitive. This may soon change as IPTG has recently become available commercially as a rather inexpensive commodity.* Consequently, while to date IPTG and its variously protected derivatives have been only seldom used in carbohydrate synthesis (e.g., References [3-5]), the substance may soon become one of the standard tools in synthetic carbohydrate chemistry, opening avenues toward an array of complex galactosyl donors and acceptors.