Saturated oxygen heterocycles
Mark C. Elliott and Eve Williams
Department of Chemistry, Cardiff University, PO Box 912, Cardiff, UK CF10 3TB
Received (in Cambridge, UK) 7th June 2001
First published as an Advance Article on the web 18th September 2001
Covering: 1 July 1999 to 31 December 2000. Previous review: J. Chem. Soc., Perkin Trans. 1, 2000, 1291.1
1 Introduction
2 Three-membered rings
3 Four-membered rings
4 Five-membered rings
5 Six-membered rings
6 Medium sized rings
7 References
1 Introduction
As with previous reviews in this series, the recent literature on
three to nine-membered oxygen heterocycles has been surveyed.
Only those systems with a single heteroatom have been covered,
with the exclusion of cyclic acetals and ketals. Again, while
sugar derivatives have not been generally included, there are
inevitably examples of pyran synthesis which owe much to this
rich area of chemistry.
Given the large number of publications in this area, no
attempt has been made at comprehensive coverage. We have
elected to focus on short communications for the most part,
with full papers describing work covered in the previous reviews
merely being cited and not discussed in detail. Where previous
work has been alluded to without citation, these references can
be found in the previous reviews.
2 Three-membered rings
The Jacobsen–Katsuki epoxidation has generated interest from
a number of groups. Jacobsen’s own recent work in this area
has concentrated on asymmetric ring-opening of epoxides
using cobalt–salen complexes.2 One particularly useful result
from this work is the enantioselective Payne rearrangement
shown in Scheme 1.3 The corresponding chromium complex is
more efficient for the kinetic resolution of 2,2-disubstituted
epoxides by azide ring-opening.4 Two groups have reported
the asymmetric ring-opening–kinetic resolution of epoxyphos-
phonates.5
Dendrimers bearing eight Co–salen complexes show dramat-
ically enhanced catalytic activity in this reaction, which is
Scheme 1
believed to involve two metal centres,