1-Pyrrolidino-l-cyclohexene

In general the Stork reaction gives moderate yields with simple alkyl halides better yields of alkylated product are obtained with more electrophilic reactants such like allylic, benzylic or propargylic halides or an a-halo ether, a-halo ester or a-halo ketone. An example is the reaction of 1-pyrrolidino-l-cyclohexene 6 with allyl bromide, followed by aqueous acidic workup, to yield 2-allylcyclohexanone ... 

A novel ring closure was discovered by Stork (6) in which the pyrrolidine enamine of a cycloalkanone reacts with acrolein. The scheme illustrates the sequence in the case of 1-pyrrolidino-l-cyclohexene, and the cyclopentane compound was found to undergo the reaction analogously. The procedure details the preparation of the bicyclo adduct and its cleavage to 4-cyclooctenecarboxylic acid. 

The complicated reaction of 1-pyrrolidino-l-cyclohexene with quinonebenzenesulfonimide may begin with arylation of the enamine system.234 The final product of the strongly exothermic reaction is a substituted tetrahvdrocarbazole (66). 

Vinylic isocyanates react with enamines such as 1-pyrrolidino-l-cyclohexene under mild conditions to form a new pyridinone ring and simultaneous loss of pyrrolidine [3S40]. Reaction of an ynaminone with phenyl isocyanate in refluxing THF gives good yields of 3-acyl-4-dimethylamino-2-quinolinone [2056]. A perchloroynamine behaves similarly [2838]. 

Cycloaddition of nitrones with cyclanone enamines are extensively investigated. The reaction is regio- and stereospecific, and always gives one product. Thus, nitrones 10k, when caused to react with 1-pyrrolidino-l-cyclohexene, give the 5-pyrrolidinoisoxazolidine (13a), and with 1-pyrrolidino-l-cyclopentene, the isoxazolidine (13b).60 72-74... 

The benzamide bisdiene 134 proved to be a particularly good substrate for the carbocyclization with 1-pyrrolidino-l-cyclohexene. Its cyclization using 2 equiv of triph-enylphosphine or tris(o-tolyl)phosphine or 1 equiv of diphenylphosphinoethane (dppe) in conjunction with Pd(OAc)2 proceeds in about 90% overall yield to the substituted N-acylpyrrolidine 135 (Scheme 43). Notably, indole also proves to be an effective trapping reagent in the reaction of 134. The adduct 136 is obtained in 91% yield from the palladium acetate-catalyzed reaction in the presence of lris(( -tolyl)phosphine. 

A soln. of 1-pyrrolidino-l-cyclohexene and propylene oxide in dimethylform-amide heated 25 hrs. at 150 in an evacuated sealed vessel, treated with water, and refluxed 0.5 hr. 2-(2-hydroxypropyl)cyclohexanone. Y 60%. F. e. s. A. Z. Britten, W. S. Owen, and C. W. Went, Tetrahedron 25, 3157 (1969). 

Pyrrolidino-l-cyclohexene added dropwise to a soln. of 2 moles of allyl bromide and 2 moles of N-ethyl-N,N-dicyclohexylamine in chloroform, refluxed ca. 12 hrs., then hydrolyzed by refluxing 1-2 hrs. with dil. HGl 2,6-diallyl-cyclohexanone. Y 95%. F. e., also monoalkylation, s. G. Opitz, H. Mildenberger, and H. Suhr, A. 649, 47 (1961). 

Related Reagents. Allyltrimethylsilane 3-Bromo-l-trimethylsilyl-l-propene 1-Pyrrolidino-l-cyclohexene Tetrakis-(triphenylphosphine)palladium(O) Trimethylsilylallyllithium. 

The 2,2 -dialkylation of enamines has been used for the synthesis of novel bi- and trieyeloketones (id). Alkylation of 1-N-pyrrolidino-l-cyclohexene (28) with 1,4-diiodobutane gave a 15% yield of bicyelo[1.3.4]-10-decanone (35), while alkylation with o-xylylenedibromide gave a 31 % yield of 2,6-o-xylyleneeyelohexanone (36). 

A similar mechanism is thought to be involved in the formation of a-trilluoromethyl ketone 7 instead of expected amine 6 during the reaction of iminium salt 5 with CF3Br under Barbier conditions (equation 4) . It was proposed that pyridine probably transforms iminium ion 5 into the enamine (l-pyrrolidino)-l-cyclohexene by elimination of HQ, which then undergoes a radical chain reaction with CF Br as shown in Scheme 1 to give 7. This is supported by the observation that no condensation products are observed when iminium salts lacking removable a-hydrogens are used. 

One advantage observed with this reagent is that dichlorinated ketones are not observed. Moreover, the stereochemistry of the reaction can be controlled by the experimental conditions as shown in the chlorination of 6-methyl-l-pyrrolidino-l-cyclohexene (1), which can lead selectively to either cis- or trans-... 

Cyclohexan trans-2-Hydroxy-l-pyrrolidino- Vl/la, 1, 527, 529 Cyclohexen rans-3-Butylamino-4-hydroxy-E16d, 1209 (Amin 4-Oxiran)... 

Chloro-5-phenyl-l,2-dithiolium perchlorate reacted with 1-pyrrolidino-cyclopentene (or cyclohexene), to give, after hydrolysis, a dithiolylidene ketone. Hydrosulfolysis of the same reaction product gave the corresponding trithiapentalene. ... 

Enamines have been observed to act both as dienophiles (46-48) and dienes (47,49) (dienamines in this case) in one-step, Diels-Alder type of 1,4 cycloadditions with acrylate esters and their vinylogs. This is illustrated by the reaction between l-(N-pyrrolidino)cyclohexene (34) and methyl t/-a i-2,4-pentadienoate (35), where the enamine acts as the dienophile to give the adduct 36 (47). In a competitive type of reaction, however, the... 

The reaction of an alicyclic enamine with benzyne intermediate yields simple arylation products and/or 1,2-cycloaddition products, depending upon the reaction conditions 102). This is illustrated by the reaction of l-(N-pyrrolidino)cyclohexene with benzyne (86) (obtained from fluoro-benzene and butyl lithium or o-bromofluorobenzene and lithium amalgam), which produces benzocyclobutene 87 102). 

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