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Syntheses and reactions of novel 3-heterospiro[5.5]undecan-9-ones

F. Sauter, J. Fröhlich and M. Pfalz

Institute of Organic Chemistry, Technical University of Vienna, Getreidemarkt 9, A-1060 Vienna, Austria

Overview

Here, we present the preparation and reactions of heteroatom-containing spiro compounds of the following types:

A key reaction step in the synthesis of the 3-heterospiro[5.5]undec-7-en-9-ones (A) is the Robinson annulation of an aliphatic 4-substituted heteroatom-containing aldehyde (D) with methylvinylketone.

The preparation of these 4-substituted heteroatom-containing aldehydes (D) required as starting materials also turned out to be a synthetic challenge.

The 3-heterospiro[5.5]undecan-9-ones (B) obtainable from their enone-precursors served as starting materials in the synthesis of various heterocycles (E) as well as substrates for a Schmidt rearrangement to yield 3-hetero-9-azaspiro[5.6]dodecan-10-ones (F).

The 3-heterospiro[5.5]undec-7,10-dien-9-ones (C) underwent a dienone-phenol rearrangement to yield benzo[d]heteroepan-7-oles (G) under strong acidic conditions.