Allyl amines, cyclopropanation

Photochemical Fe(CO)5-induced rearrangement of silylated allyl amine 9 gave N-silylated enamine 1015, which on subsequent Cu-catalyzed cyclopropanation by methyl diazoacetate afforded cyclopropane derivative 11. The use of an optically active catalyst gave an asymmetric induction of 56% ee for the cis isomer and 20% ee for the trans isomer. Further acid-induced ring cleavage afforded the -formyl ester 12, whereas reduction and desilylation produced aminocyclopropane carboxylic acid 13 (equation 2). 

Allyl sulfides and allyl amines. Rhodium-catalyzed decomposition of ethyl diazoacetate in the presence of these allyl compounds generates products 136 and 137, respectively, derived from [2,3] rearrangement of an S- or N-ylide intermediate, besides small amounts of carbene dimers No cyclopropane and no product resulting from the ylide by [1,2] rearrangement were detected. Besides RhjfOAc) and Rhg(CO)i6, the rhodium(I) catalysts [(cod)RhCl]2 and [(CO)2RhCl]2 were found to behave similarly, but yields with the only allyl amine tested, CH =CH—CH NMe, were distinctly lower with the latter two catalysts. Reaction temperatures are higher than usually needed in rhodium-promoted diazoalkane decomposition, which is certainly due to competition between the diazo compound and the allylic hetero-... 

Example 3, Diastereoselective Simmons-Smith cyclopropanations of allylic amines and carbamates ... 

The allylpalladium chloride dimer (1) has served as an excellent precursor of active catalyst for hydroamination of various substrates such as methylenecyclopropanes, enynes, and dienes. The reaction of (4-phenylbutylidene)cyclopropane with amines in the presence of 5 mol % of dimer (1) and dppp, (l,3-bis(diphenylphos-phino)propane), gave the corresponding allylic amine in 31-91% yield (eq 92). It is noteworthy that Pd precursors such as Pd2(dba)3 CHCl3, Pd(PPh3)4, or PdCl2(PPh3)2 were less efficient Pd(OAc)2 did not promote the reaction. 

The stereoselectivity of cyclopropanation is highly affected by the stereogenic centers close to the alkene unit. Aggarwal et al. reported that A -chiral allylic amine 96 underwent stereoselective cyclopropanation to give 97 in 95% yield (Scheme 1.50) [85]. The obtained product 97 was almost a single isomer. 

ETHYLENE GLYCOL ETHYL MERCAPTAN DIMETHYL SULPHIDE ETHYL AMINE DIMETHYL AMIDE MONOETHANOLAMINE ETHYLENEDIAMINE ACRYLONITRILE PROPADIENE METHYL ACETYLENE ACROLEIN ACRYLIC ACID VINYL FORMATE ALLYL CHLORIDE 1 2 3-TRICHLOROPROPANE PROPIONITRILE CYCLOPROPANE PROPYLENE 1 2-DICHLOROPROPANE ACETONE ALLYL ALCOHOL PROPIONALDEHYDE PROPYLENE OXIDE VINYL METHYL ETHER PROPIONIC ACID ETHYL FORMATE METHYL ACETATE PROPYL CHLORIDE ISOPROPYL CHLORIDE PROPANE... 

Palladium-catalyzed methylene transfer from diazomethane has proved effective for the cyclopropanation of 1-alkenylboronic acid esters allylic alcohols and amines 1-oxy-l,3-butadienes and allenes " Readily accessible iron complex (CO)2FeCH2S Me2 BF4 35 undergoes direct reaction with a range of alkenes to give cyclopropanes (equation 67) The salt is sensitive to steric effects and the reaction proceeds... 

During the reaction of the doubly activated allyl halides with primary and secondary amines no 2-amino-substituted cyclopropane derivatives could be isolated, but instead ring-opened products are formed. Primary amines give rise to the formation of aldimines (332) while secondary amines afford formally substitution products (333) . The formation of these products can be explained by ring cleavage of non-isolable electrophilic 2-aminocyclopropanes (331) as outlined in equation 104. 

Allyldiethylamine behaves similarly, but the yields are low since neither the starting amine nor the products are stable to the reaction conditions. For the efficiency of the cyclopropanation of the allylic systems under discussion, a comparison can be made between the triplet-sensitized photochemical reaction and the process carried out in the presence of copper or rhodium catalysts whereas with allyl halides and allyl ethers, the transition metal catalyzed reaction often produces higher yields (especially if tetraacetatodirhodium is used), the photochemical variant is the method of choice for allyl sulfides. The catalysts react with allyl sulfides (and with allyl selenides and allylamines, for that matter) exclusively via the ylide pathway (see Section 1.2.1.2.4.2.6.3.3. and Houben-Weyl, Vol. E19b, pll30). It should also be noted that the purely thermal decomposition of dimethyl diazomalonate in allyl sulfides produces no cyclopropane, but only the ylide-derived product in high yield.Very few cyclopropanes have been synthesized by photolysis of other diazocarbonyl compounds than a-diazo esters and a-diazo ketones, although this should not be impossible in several cases (e.g. a-diazo aldehydes, a-diazocarboxamides). Irradiation of a-diazo-a-(4-nitrophenyl)acetic acid in a mixture of 2-methylbut-2-ene and methanol gave mainly l-(4-nitrophenyl)-2,2,3-trimethylcyclo-propane-1-carboxylic acid (19, 71%) in addition to some O-H insertion product (10%). ... 

Carbenoid attack at the heteroatom of allylic halides, ethers, amines, sulfides, and selenides generates an allylic ylide 23 that can undergo [2,3] sigmatropic rearrangement and, less frequently, [1,2] insertion (C-X insertion with and without allylic rearrangement, respectively). Similarly, an Af-acyl-2,5-dihydropyrrole could be cyclopropanated with ethyl diazoacetate in good yield. 

A variety of diverse synthetic methods have been empioyed for the preparation of cyclopropane (1 j. Schlatter and Demjanov and Dojarenko pyrolyzed cyclopropyltrimethylammonium hydroxide at 320°C using platinized asbestos as the catalyst. About equal amounts of cyclopropene (1) and cyclopropyidimethylamine are formed, contaminated with some dimethyl ether and ethylene. Treatment with dilute hydrochloric acid removed the amine from the gas stream and 1 was separated from the other products by gas chromatography. Alder-Rickert cleavage of the Diels-Alder adduct formed from cycloheptatriene and dimethyl acetylenedicarboxylate resulted only in the formation of a polymer and trace amounts of 1. A simple approach by Closs and Krantz based on the synthesis of 1-methylcyclopropene involved the addition of allyl chioride to a suspension of sodium amide in mineral oil at 80°C. Under the conditions employed, 1 could readily escape from the reaction mixture. Though a number of variations were tried, the yield of 1 never exceeded 10%. 

More unexpected was the formation of cyclopropane during the indium-mediated reaction of dibenzylidene acetone with allyl bromide which gave l,l-distyryl-2-(but-3-enyl)cyclopropane as a mixture of four isotopomers (Scheme 31) [158]. In a related reaction, a simple and efficient one-pot method was developed to give chiral homoallylic amines and amino acids from the respective aldehydes with high stereoselectivity [159]. 

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