Bonds reaction with diazomethane

Chiral electrophilic cyclopropanes (63) are prepared in high enantiomeric excess starting from butadiene-iron tricarbonyl complexes (60) containing a non-complexed double bond. Reaction with diazomethane and decomposition of the resulting pyrazolines (61) in the presence of Ce" gave the corresponding chiral cyclopropanes (62). Breakdown of the dienic substituent of electrophilic cyclopropane (62) by means of ozonization resulted in the formation of formyl-substituted electrophilic cyclopropane (63) still carrying the asymmetric centre (equation 10) " . ... 

Because of the high polarity of the C=N double bonds, cyanuric chloride (120, R= Cl) is comparable with a carboxylic acid chloride. This explains its smooth reaction with diazomethane to yield dichloro-(diazomcthyl)-l,3,5-triazine (121, R = The analogous com-... 

The formation of isocyanates has also been observed in reactions outlined in equations (21)-(23). It has been shown that the reactions of equation (21) most probably proceed via coordination of the amine function followed by rearrangement with elimination of HX. The reaction with PPh3 is interesting because of the initial formation of a nitrene species via N—O bond cleavage. Formation of a nitrene intermediate as a crucial step in the formation of the NCO ligand has also been proposed for the reaction with diazomethane. 

Unsaturated 5(4//)-oxazolones have an additional exocylic double bond which has been exploited in various reactions. Chiral oxazolone 120 undergoes diastereoselective reaction with diazomethane to give cyclopropane adduct 121, which can be transformed into various cyclopropylamino acids 122 (Scheme 29) <1996T5881>. 

In contrast to the reaction with diazomethane, the cyclopropanation of cyclopropylidene(di-spiro[2.0.2.1]heptylidene)methane (15) with diiodomethane/diethylzinc took place predominantly at the reactive central double bond. The product of double cyclopropanation was also obtained in good yield. 

Diazomethane generated in the presence of palladium compounds has been shown to undergo addition to the double bond of the norbornene fragment of the cyclopentadiene dimer, e.g. formation of 14 and 15.25 26 This was attributed to the formation of a tt-alkene complex of palladium with the norbornene double bond and its subsequent reaction with diazomethane.27... 

Irradiation of the pyrazoline mixture 12, 13, and ( )-14 yielded methanofullerenes 15 and 16 (7 1) with a closed transannular 6 - 6 bond besides minor amounts of a third constitutional isomer (17), whereas thermolysis of the same mixture gave 17 and inherently chiral ( )-18 (4 l),both constituting core-modified fullerenes [76] (Scheme l).With open transannular 6-5 bonds , the functionalized regions of 17 and ( )-18 resemble methanoannulene sub-structures. [3 + 2]Cycloaddition of alkyl azides to C70 affords triazolines which are isolable when the temperature does not exceed ca. 50 °C. Similar to the reaction with diazomethane, three constitutionally isomeric adducts were observed [77,113], and the regioisomer of type 19 [113] with the substituent of the heterocycle located above the apex of C70, predominated over its regioisomer of type 20 in two in-... 

Short peptide chains in which one of the amino acid residues is replaced by a moiety related (or sometimes unrelated) to it appear with increased frequency in the literature. In the center of interest are enzyme inhibitors. Synthesis of these compounds is obviously determined by the reactivity of the unusual constituent and therefore it is hardly possible to set rules for such endeavours. We must confine the discussions therefore to generalities. For example chloromethylketones derived from certain amino acids are irreversible inhibitors which not merely interact but indeed react with the active site of an enzyme with the formation of a covalent bond. Chloromethyl ketones are synthesized by activation of the blocked amino acid followed by reaction with diazomethane to yield a diazoketone. This is transformed to the corresponding chloromethyl ketone by HCl in an organic solvent. From p-toluenesulfonyl-L-phenylalanine a chloromethyl ketone is obtained... 

The grevillins are easily converted into crystalline yellow peracetyl derivatives with acetic anhydride and a trace of concentrated sulphuric acid (Table 2) 204, 461, 603). On catalytic hydrogenation the grevillins yield colourless dihydro derivatives in which reduction of the exocyclic double bond has taken place 603). Conjugate addition of nucleophiles to the exocyclic enone system leading to colourless by-products has also been observed during acetylation of these pigments 101) and in their reaction with diazomethane in methanol 276, 461). 

In organorhodium compounds, reaction with diazomethane [50-52], and rearrangement with acetylene compounds, etc. [53-62], afford a variety of carbene complexes. The carbenes are a general term for a chargeless divalent carbon (X(Y)C ) and the triplet state bond angle is ca. 150°) is more stable by ca. lOkcal/moI than the singlet state (bond angle ca. 100°). The metal complexes of a carbene are represented as M=CRR and when R and R are C or H, it is called an alky-lidene complex. The carbene is labile, but the carbene complexes are relatively stable. 

Tetrakis(trifluoromethyl)furan 137 was obtained in 79 % yield by thennolysis of tricyclic compound 219 which was synthesized from valence-bond isomer of hexakis(lrifluoromethyl)oxepin 218 via the reaction with diazomethane [139]. This compound was also obtained by bromine-induced isomerization of 3-trifluoroacetyl-l,2,3-tris(trifluoromethyl)cyclopropane 220 [140],... 

Organogermanium chlorides (and indeed GeCLt also) undergo an interesting and often useful reaction with diazomethane to replace chlorine ligands with chloromethyl groups, thereby establishing new Ge-C bonds fi ... 

Hydroxypyridine 1-oxide is insoluble in chloroform and other suitable solvents, and, although the solid-state infrared spectrum indicates that strong intermolecular hydrogen bonding occurs, no additional structural conclusions could be reached. Jaffe has attempted to deduce the structure of 4-hydroxypyridine 1-oxide using the Hammett equation and molecular orbital calculations. This tautomeric compound reacts with diazomethane to give both the 1- and 4-methoxy derivatives, " and the relation of its structure to other chemical reactions has been discussed by Hayashi. ... 

The Lewis acid-Lewis base interaction outlined in Scheme 43 also explains the formation of alkylrhodium complexes 414 from iodorhodium(III) meso-tetraphenyl-porphyrin 409 and various diazo compounds (Scheme 42)398), It seems reasonable to assume that intermediates 418 or 419 (corresponding to 415 and 417 in Scheme 43) are trapped by an added nucleophile in the reaction with ethyl diazoacetate, and that similar intermediates, by proton loss, give rise to vinylrhodium complexes from ethyl 2-diazopropionate or dimethyl diazosuccinate. As the rhodium porphyrin 409 is also an efficient catalyst for cyclopropanation of olefins with ethyl diazoacetate 87,1°°), stj bene formation from aryl diazomethanes 358 and carbene insertion into aliphatic C—H bonds 287, intermediates 418 or 419 are likely to be part of the mechanistic scheme of these reactions, too. 

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