Ethylidenation of olefins using a convenient iron-containing cyclopropanation reagent

Abstract

Wavelength (nm) Figure 2. Visible absorption spectra at 25 "C for the photodecomposition of 3-azido-9-[[4-(diethylamino)-l-methylbutyl]amino]-7-methoxyacridine. Spectra A-H correspond to 0, 5, 10, 20, 30,40, 50, and 60-s irradiations of a 1.078 X M solution of the azide in 30 mM phosphate, pH 3.0. The solutions were irradiated in a Rayonet RPR-100 photochemical reactor using four RPR-3500-A lamps. The inset plots show A357 (0) and the logarithm of the observed A357 minus A357 observed at 60-s irradiation time ( . ) against time.removed in this way. The yield of crystalline product was 50%: mp 161-162 OC, dec; u, , (CHC13) 2120 cm-I. Anal. Calcd for Displacement of the chloro substituent from VI11 to give the quinacrine azide analogue I1 was carried out by heating a mixture of the 2-amino-5-(diethylamino)pentane (1.33 equiv) with the chloroacridine (VIII) and phenol at 100 OC for 3 h. The mixture was then taken up in ether and dry hydrogen chloride gas bubbled through it to precipitate the hydrochloride salt: mp 173 OC, dec; u, (CHC13) 21 10 cm-I. Anal. Calcd for Cz3Hz~N60-2HC1. Hz0: C, 55.53; H, 6.89; N, 16.89; C1, 14.24. Found C, 55.37; H, 6.43; N, 16.44; C1, 13.78. Figure 2 shows the photosensitivity of the quinacrine azide product which appears to smoothly decompose in a 60-s irradiation with 350-nm light. The inset plot for Figure 2 shows the absorbance plotted for the 357-nm maximum and log (Ai -A) plotted against time. A tl/z.of 8-10 s is observed for the first-order photodecomposition. Similar data are obtained from the absorbances at 423 nm. An isosbestic point at 460 nm is also observed for the photodecomposition reaction. The photosensitivity of I1 is not pH dependent. Photodecomposition kinetics virtually identical with those seen in Figure 2 have been observed at pH 7.2 (30 mM phosphate). We have not investigated the photochemical products for the irradiation of I1 or any of the other azido intermediates all of which are comparably photosensitive. It is important to note that most biological systems are relatively insensitive to irradiation with 350-nm light of such intensity and duration as is needed to photodecompose 11. The photosensitivity of I1 appears to be comparable to other organic azides which have proven useful in photochemical labelingz6Both work in our laboratory and elsewhere suggest that these azides will prove useful in photochemical labeling experiments. Mair and Stevens6 have shown that azide in the 3-position on the acridine ring gives rise on irradiation to complex mixtures of products which they assumed to result from a variety of reactions of the generated reactive nitrene. In our more biologically interesting azidoacridines there is a similar photoproduct complexity. In contrast Mair and Stevens showed that the azide in the 9-position of the acridine ring results in a long-lived nitrene. Such nitrenes may survive many collisions with solvent and form an azo dimer as a principal product. Other positions of the acridine ring do not appear to have been investigated. (26) Chowdhry...

Synthesis of Open‐Chain 2,3‐Disubstituted 4‐nitroketones by Diastereoselective Michael‐addition of (E)‐Enamines to (E)‐Nitroolefins. A topological rule for C, C‐bond forming processes between prochiral centres. Preliminary communication

“…In agreement with the preference of topology 10 (syn-donor) over topology 11 (anti-donor), anti-enolates (entry 7) furnish lower selectivity (61 and react more slowly [6] ( c j [45]), in spite of the fact that their R2-group is in a quasi-equatorial position [6]. C j the erythro-selectivity of the addition of lithiated ally1 methyl nitrosamine to benzaldehyde [59].…”

“…In agreement with the preference of topology 10 (syn-donor) over topology 11 (anti-donor), anti-enolates (entry 7) furnish lower selectivity (61 and react more slowly [6] ( c j [45]), in spite of the fact that their R2-group is in a quasi-equatorial position [6]. Some examples suggest that the above rule does not hold, when very bulky groups R1, R2 and substituents on Y are presenti3) [5] [6] 191 [37-391.…”

“…The product in entry 11 is (RS; S R ) when R = aryl and (RR; S S ) when R = alkyl. Instead of the plain lone pair of electrons at the singlet carbene centre, a metal complex (RCH= M+) [45][46][47] might be more appropriate here. Sulfur ylids, which are much less stable, do not react selectively under the conditions usually employed [48], i.e.…”

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

“…The choice of the metal also plays an important role, particularly if the reaction is not thermally induced, but photochemically. 187 Neidlein et al [860][861][862] have prepared 2-[1,6-methano [10]annulenyl]-substituted Fischer carbene complexes. While the chromium complex underwent the normal benzannulation reaction with alkynes to give quinones and hydroquinones, depending on the work-up conditions, 862 the respective tungsten complex did not CO insert and gave 540.…”

New chemical and stereochemical applications of organoiron complexes

“…As observed earlier by Pettit et al [ 211 ], and others [ 212 ], when methoxymethyliron complex 45 was treated with acid, it underwent cleavage to a short-lived, cationic methylidene complex 46, as evidenced by the formation of norcarane 47 when the cleavage was performed in the presence of cyclohexene ( Scheme 10 ). Several methods have been developed for the preparation of more-stable metal carbenes suitable for cyclopropanation [ 213 ]; some of these require replacement of the simple methylidene group by an ethylidene [ 172 ], isopropylidene [ 159 , 214 ], allyhdene [ 185 , 215 ], or benzylidene [ 216 ] group.…”