A facile synthesis of α-d-galactopyranosyl-(1 → 1)-α-d-galactopyranoside and its analogues

✍ Scribed by Rimon H. Youssef; Rafik W. Bassily; Adel N. Asaad; Ramadan I. El-Sokkary; Mina A. Nashed

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 242 KB
• Volume: 277
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(95)00226-j

✦ Synopsis

In a previous paper [1] we reported the synthesis of trehalose esters of corynomycolic acid, the simplest of the mycolic acids, for studies of trehalose:mycoloyl transferase [2]. We have also reported [3] the synthesis of the gluco-galacto analogue of trehalose for the same purpose. Trehalosamines have been isolated from microorganisms [4] or synthesized [5] and found to have antimicrobial activity [6]. In the present study, we describe the synthesis of trehalose analogues having various sugar residues, such as D-galactose and 4,4'-diazido-D-galactose, which represents a potential, preparative precursor for the corresponding 4,4'-diaminotrehalose.

Synthetic routes to the galacto-galacto trehalose analogue have been investigated by several groups [7][8][9][10]. Birch and Richardson [7] and Goren and co-workers [10] prepared galacto-galacto trehalose from dibenzylidene trehalose by multistep reactions. Also, Pavia et al. [9] prepared the same compound from the monosaccharide building blocks. The disadvantage of this procedure was in the lack of stereoselectivity. Our results, presented herein, reveal some unanticipated advantages of this latter approach.

Symmetrical trehalose hexabenzoate [3] (1) was prepared from the tributylstannyl derivative as described by Ogawa and Matsui [11]. The ready availability of the key intermediate 1 permitted the synthesis of symmetrically substituted galacto-trehalose. Acylation of the OH-4,4' groups of 1 with trifluoromethanesulfonic anhydride (triflic * Corresponding author.