Brønsted acid-promoted azide–olefin [3 + 2] cycloadditions for the preparation of contiguous aminopolyols: The importance of disiloxane ring size to a diastereoselective, bidirectional approach to zwittermicin A

• Hubert Muchalski,
• Ki Bum Hong and
• Jeffrey N. Johnston

Beilstein J. Org. Chem. 2010, 6, 1206–1210, doi:10.3762/bjoc.6.138

• diol. This development provides a basis for a stereocontrolled approach to the aminopolyol core of (−)-zwittermicin A using a bidirectional synthesis strategy. Keywords: azide; bidirectional synthesis; cycloaddition; dialkoxydisiloxane; TIPDS; triazoline; triflic acid; zwittermicin A; Introduction

• Structural motifs such as 1,2-aminoalcohol, 1,2- and 1,3-diol are very prevalent features in natural products, especially polyketides. The structures of some of these, such as sorbistin A1 [1] or zwittermicin A [2], contain mostly aminopolyol moieties. Aminoalcohol and diol motifs are often constructed via

• aminohydroxylations [6][7][8]. Triflic acid-promoted reaction of an alkyl azide with an α,β-unsaturated imide delivers a formal anti-aminohydroxylation product. We wondered whether azide–olefin functionalization could be used to prepare the complex aminopolyol core of zwittermicin A [9][10][11][12]. We were