1,3-Dipolar cycloaddition reactions to the C:X-M fragment. 9. Synthesis and characterization of mononuclear imino ketone complexes Fe(CO)3(tert-BuN:CHCR:O) and their use in chemoselective cycloaddition reactions with dimethyl acetylenedicarboxylate resulting in the formation of Fe(CO)3(butenolide) complexes

1,3-Dipolar cycloaddition to the FeSC fragment 20. Preparation and properties of carbonyliron complexes of di-thiooxamide. Reactivity of the mononuclear (di-thiooxamide)Fe(CO)3 towards dimethyl acetylenedicarboxylate

“…(2) 74.58(3) S(1) C(1) C(2) 120.1(2) 100.03 (11) N(2) C(5) C(4) Fe(1) S(2) C (2) 111.1(2) N(2) C(1) C (2) 120.8(2) Fe(2) S(2) C (2) Fe(1) C(7) O(7) 65.02 (10) 179.0(3) Fe(2) C(2) S (2) 67.16(11) 119.5 (2) Fe (1) …”

“…It has been demonstrated in the previous parts of this series that the initial step in these reactions consists of a 1,3-dipolar cycloaddition reaction of the activated alkyne (dipolarophile) across the M N C fragment (1,3-dipole), resulting in the formation of the bicyclo [2.2.1] intermediate 2. In order to extend the synthetic potential of this reaction we studied the reaction of the isostructural mononuclear Fe(CO) 3 (NO) (NO = a-iminoketone and a-iminoester) complexes and found that they react via a similar reaction sequence [9,10]. This was proven by the solid state structure of the initial bicyclo[2.2.1]Fe(Ph 2 PCH 2 CH 2 PPh 2 )(CO) adduct 6 [11] and the isolation of the stable adducts 2 (cf.…”

“…From these investigations two important conditions with respect to the 1,3-dipolar reactivity emerged; (i) since the Fe X C (X= NR, O) fragment can be classified as nucleophilic type I 1,3-dipole [22][23][24][25][26][27], a relatively high electron density is required [1,6,8,10,[28][29][30], and (ii) because the cycloaddition proceeds over the Fe X C (X= NR, O) fragment, the metal atom must be able to increase its co-ordination number and oxidation state.…”

Reactions of a quintuply bonded chromium dimer with alkynes

“…In transition metal chemistry, the compounds most closely related to 3 are Fru¨hauf's products of 1,3 dipolar additions across M-XQC bonds (X = O, S, N). [19][20][21][22][23][24][25] In main group chemistry, the reversible addition of alkynes to dinuclear gallium complexes of a chelating diamide provides a recent analogue. 26 However, what makes 3 unique is the apparent retention of its metal-metal multiple bond.…”

Ruthenium Carbonyl-Catalyzed [2 + 2 + 1]- Cycloaddition of Ketones, Olefins, and Carbon Monoxide, Leading to Functionalized γ-Butyrolactones

“…Although the mechanism for this reaction is not clear, the coordination of 1-aza-4-oxo-1-diene (NC−CO) in N - heterocyclic ketones or 1,4-dioxa-1,3-diene (OC−CO) in α-dicarbonyl compounds to ruthenium leading to σ-X, σ-O chelate ruthenium carbonyl complexes (X = N or O) or the related metallacycles would be a key step for the present cyclocoupling reaction to proceed. One possible mechanism is shown in Scheme . − The coordination of a substrate 19 to “Ru(CO) 3 ” forms a σ, σ-chelate ruthenium complex 20 . The complex 20 reacts with ethylene to form metallacycle 21 , with the coordination of X to ruthenium remaining intact.…”