Nitrosoalkenes: Synthesis and Reactivity

Abstract

SummarySome (1-and 8-halonitrosoalkenes 1 have been synthesized and characterized. The halogen atoms of the oxime precursors 2 can be substituted by alkoxy groups. Two kinds of cycloaddition reaction of 1 have been observed: i) reaction of the NO group with dienes gives 3,6-dihydrooxazine derivatives 6 which isomerise to epoxyepimines 7 in most cases of 8-substituted nitrosoalkenes: ii) if 4,5-dihydrooxazines 22 are obtained, the cycloaddition of the nitrosoalkenes as 4 7r-component is presumed.Nitrosoalkenes possess a large synthetic potential, since they comprise both an alkene activated by an electron withdrawing group and an 1,3-diene system. Furthermore, the nitroso group itself reacts with it wide number of reagents [l] and allows an easy, simultaneous incorporation of nitrogen and oxygen by addition We have recently reported the epoxy-epimination of cyclic 1,3-dienes by isomerization of the cycloadducts formed from such dienes with certain halonitrosoalkenes [6] [7]. This reaction merits particular attention since nitrosoalkenes are readily accessible, highly reactive intermediates which can be used in situ. In order to study the scope and limitations of this stereospecific reaction, which allows the functionalization of the four sp2-centres of a diene in one step, it seemed interesting to vary the dienes and the substituents of the nitrosoalkene.') Taken in part from the Ph. D-Thesis of E. Francotte (l078), present address: C'iha-Geigy AG, Zentrale Forschung. CH-4002 Basel.0018-019X/81/4/1208-11$01.00/0 0 198 I Schweizer-ische Chemiache Gesellschaft

The chemistry of isatins: a review from 1975 to 1999

“…It has been previously postulated, although never unambiguously demonstrated, that an intermediate dichloronitrosoalkene is initially formed by elimination of HCl from chloraloxime during the Sandmeyer isonitrosoacetanilide synthesis. This nitrosoalkene is subsequently attacked by the aniline to give an addition product that yields the isonitrosoacetanilide via a subsequent hydrolysis reaction 30,31 . However, competitive addition of water and aniline to the nitrosoalkene would lead to formation of the glyoxylic acid oxime and the isonitrosoacetanilide respectively.…”

Generation, Microwave Spectrum, andAb InitioMO Calculation oftrans-1-Nitrosopropene, CH3CHCH—NO (synform)

“…Francotte et al have prepared and characterized a series of halonitrosoalkenes by treating the ␣-polyhalooximes with NaHCO 3 or K 2 CO 3 in dichloromethane (1). Only the nitrosoolefin of Cl 2 C|C(CH 3 )-NO could be isolated purely at room temperature, whereas the others were stable in solution for a few weeks and could be kept for months at Ϫ20°C.…”

“…Most of the transient nitrosoalkenes have been characterized by in situ cycloadditions (vide infrared spectrum) (1). Their instability can be explained by the ready decomposition of an intermediate oxazete (four-membered ring molecule) produced by intramolecular cyclization (1).…”

“…Nitrosoalkenes possess a large synthetic potential since they are comprised of both an alkene activated by an electron withdrawing group of nitroso one and 1,3-diene system having two double bonds of the C|C and N|O groups (1). Furthermore, the nitroso group itself reacts with a wide number of reagents (2) and allows an easy and simultaneous incorporation of the nitrogen and oxygen by the addition reactions (DielsAlder (3), ene-reaction (4), and (2 ϩ 2)-cycloaddition (5)).…”

The thermal isomerization of bicyclic oxazines into epoxyepimines. A preliminary theoretical study

“…The nature of the N-substituent as well as the size of the bicyclic system of substituted oxazines 1 affect their thermal reactivity (1). Thus some oxazines decompose by cycloreversion reaction (2) whereas others isomerize via Cope rearrangement (3).…”