Dienamines reactions

The following compounds have been obtained from thiete 1,1-dioxide Substituted cycloheptatrienes, benzyl o-toluenethiosulfinate, pyrazoles, - naphthothiete 1,1-dioxides, and 3-subst1tuted thietane 1,1-dioxides.It is a dienophile in Diels-Alder reactions and undergoes cycloadditions with enamines, dienamines, and ynamines. Thiete 1,1-dioxide is a source of the novel intermediate, vinylsulfene (CH2=CHCH=SQ2). which undergoes cyclo-additions to strained olefinic double bonds, reacts with phenol to give allyl sulfonate derivatives or cyclizes unimolecularly to give an unsaturated sultene. - Platinum and iron complexes of thiete 1,1-dioxide have been reported. 

Steroidal a,j8-unsaturated ketones such as /l -3-ketones undergo a facile reaction with pyrrolidine to give the corresponding, d - -dienamines (111) (40,53). The reaction is much slower with morpholine and piperidine, which is undoubtedly due to the generation of the double bond exocyclic to the six-membered hetero rings in the step involving the dehydration of the intermediate carbinolamine (112) to the corresponding iminium ion (113). 

The reaction of enamines with perfluoro olefins has also been reported (62). Dienamines have been reported to react with ethyl acrylate at C2 to give the alkylated a,j8-unsaturated ketone derivative. Thus the dienamine (44) gave 71 in 50 % yield on reaction with ethyl acrylate in dioxane for 40 hr (63). 

The reaction has been applied to more complex enamines 13) and to dienamines 19). The reduction may be rationalized by initial protonation at the enamine carbon and subsequent decarboxylation of formate ion and addition of the hydride ion to the iminium cation. This mechanism has been given support by the reaction of the enamine (205) with deuterated formic acid 143) to give the corresponding amines. The formation of 206 on reaction with DCOOH clearly indicates that protonation at the enamine carbon is the initial step. 

A similar sequence of reactions has been shown to take place with the dienamine derived from isophorone and morpholine (77). Reaction of this enamine with trichloroacetic acid gave a trichloromethyl derivative which was not isolated but which undergoes rearrangement and hydrolysis with base to give the diene acid (210). 

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 addition of p-quinone to enamines normally produces furan derivatives, especially when the enamine possesses a 3 hydrogen (see Section III. A). 1,2 Cycloaddition is claimed to take place to give a cyclobutane derivative when p-quinone and an enamine with no jS hydrogens are allowed to react at low temperatures (51). However, little evidence is reported to verify this structural assignment, and the actual structure probably is a benzofuranol (52). Reaction of a dienamine (formed in situ) with p-quinone in the presence... 

Dienamine 56a has been reported to undergo a 1,4 cycloaddition with acrylonitrile to form bicycloaminonitrile 57 in a 74% yield (61). A recent report has indicated that both possible 1,4-cycloaddition adducts are obtained from the reaction of acrylonitrile with a 1 1 equilibrium mixture of the linear- and cross-conjugated isomers of dienamine 56b (61a). 

The reaction of methyl propiolate (82) with acyclic enamines produces acyclic dienamines (100), as was the case with dimethyl acetylenedicarboxylate, and the treatment of the pyrrolidine enamines of cycloheptanone, cyclooctanone, cycloundecanone, and cyclododecanone with methyl propiolate results in ring enlargement products (100,101). When the enamines of cyclohexanone are allowed to react with methyl propiolate, rather anomalous products are formed (100). The pyrrolidine enamine of cyclopentanone forms stable 1,2-cycloaddition adduct 83 with methyl propiolate (82). Adduct 83 rearranges to the simple alkylation product 84 upon standing at room temperature, and heating 83 to about 90° causes ring expansion to 85 (97,100). 

Dienamines undergo 1,4 cycloaddition with sulfenes as well as 1,2 cycloaddition. For example, l-(N,N-diethylamino)butadiene (111), when treated with sulfene (generated from methanesulfonyl chloride and triethyl-amine), produces 1,4 cycloadduct 116 in an 18 % yield and di-1,2-cycloadduct 117 in a 60 % yield (160). Cycloadduct 116 was shown not to be the precursor for 117 by treating 116 with excess sulfene and recovering the starting material unchanged (160). This reaction probably takes place by way of zwitterion 115, which can close in either a 1,4 or 3,4 manner to form cycloadducts 116 and 118, respectively. The 3,4 cycloaddition would then be followed by a 1,2 cycloaddition of a second mole of sulfene to form 117. Cycloadduct 117 must form in the 3,4 cycloaddition followed by a 1,2-cycloaddition sequence rather than the reverse sequence since sulfenes undergo cycloaddition only in the presence of an electron-rich olefinic center (159). Such a center is present as an enamine in 118, but it is not present in 119. 

Vinylogous forma mides have been obtained by double Vilsmeier reactions of methyl ketones (53,54), 4-methylpyridine (53,54), and olefinic (55) compounds. The dienamine intermediates were demonstrated in the latter cases. 

The stereospecific generation of enamines by -elimination reactions (187) and a vinylogous elimination, which leads to a dienamine (188), have been reported. The loss of an a substituent from a tertiary amine is seen in the generation of enamines by elimination of hydrogen cyanide from benzylic a-aminonitriles (189,190). 

Alkylation of dienamines with alkyl halides has been found to take place at the oc carbon (288-290). The reaction was used in the synthesis of steroid analogs (291). 

Note Such enamines usually react as alkenes but with deamination the dienamines also react as alkenes but usually without deamination. No added base is needed for these reactions. 

The above assumption has been supported by in vitro transformation of 4,21-didehydrogeissoschizine (32) to 5,6-dihydroflavopereirine (3) (108). Treatment of 32 with base supplied dienamine 149, which loses the (3-aldehydo ester unit attached to C-15 in a retro-Mannich reaction. Finally, two subsequent [1,5]-sigmatropic hydrogen migrations led to 5,6-dihydroflavopereirine (3), isolated as the perchlorate salt. 

Isophorone diamine (IPDA), 10 395 14 588 cis, Irares-Isophoronediamine physical properties of, 2 500t Isophorone dienamine-acrylonitrile reaction, 13 438... 

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