Jm. Jorda-gregori et al., 1,3-oxazin-2-ones vs tetrahydrofurans by iodocyclisation of 2-alkoxycarbonylamino-3-alken-1-ols, TETRAHEDR-A, 11(18), 2000, pp. 3769-3777
Iodocyclisation of primary homoallylic alcohols 2a-d, containing either a 2
-t-butoxy- or a benzyloxy-carbonylamino group, was studied, in order to est
ablish the nucleophilic group involved in cyclofunctionalisation. In fact,
the N-t-Boc derivative 2a gave the oxazinone 3, exclusively, whereas starti
ng from the N-Cbz derivative 2b a diastereomeric mixture of substituted tet
rahydrofurans 4 and 5 resulted in ratios depending upon the reaction condit
ions. These results were rationalised by means of computational methods. On
the contrary, migration of both the t-butyl or benzyl group to the hydroxy
group was observed when both 2c and 2d underwent cyclisation to give the c
orresponding 5-alkoxymethyl oxazolidin-2-ones 7a,b in low yield, but with h
igh regio- and stereocontrol. (C) 2000 Elsevier Science Ltd. All rights res
erved.