Amide acetals, bicyclic

Bicyclic amide acetals have synthetic utility, as illustrated by the catalytic reduction of (84 R1 = H, R2 = Pr") leading to amino alcohols (85) reaction of (84 R1 = OH, R2 = H) with formic acid involves double ring fission to give (86) (71S16,78MI43600). 

Reactions of nitriles with nucleophilic reagents normally require catalysis by acids or bases. Heating iminodiethanols with aliphatic nitriles in the presence of catalytic amounts of sodium alkoxide leads to oxazolo[2,3-6Joxazoles ( bicyclic amide acetals ), in a single process via oxazolidine intermediates (equation 18) (73AG(E)1055>. 

A(./V-Disubstituted chloromethyleneiminium chlorides (compare Section 2.1.2.2) react with alcoholic alkoxides at temperatures below 0 C to give amide acetals (433 Scheme 79, yields 30-70%)7" 9,24,28,30,32,35 gy the same method lactam acetals (435) are accessible. From dimethylformamide chloride and catechols the amide acetals (434) were prepared. - The bicyclic amide acetals (436) have been obtained from phenols, formamide and POCb. ... 

The action of a Zn/Cu couple on 1,3-dibromo ketones and secondary amides yields 2-dialkylamino-1,3-dioxolanes (451 equation 208). Fluorosulfonic peracid anhydride adds to trifluoroacetonitrile to give an amide acetal (452 equation 209). In the addition of (Z)-2-butene-l,4-diol to trichloroacetoni-trile, catalyzed by sodium, the 1,3-dioxepin (453 equation 210) is produced. Bicyclic amide acetals (454 equation 211) are byproducts in the reaction of lactim ethers with diketene. TTie methyl esters of perfluorinated carboxylic acids react with diethanolamine to afford bicyclic amide acetals (455 equation 212). Heating of maleic anilides (456 equation 213) with acetic acid anhydride/sodium acetate gives heterocyclic compounds (457) containing an amide acetal structure. ... 

Aluminum bromide, 10,42,140 Aluminum chloride, 10-15,140,357 Aluminum cyclohexoxide, 15 Aluminum hydride, 357 AluminumOII) iodide, 106 Aluminum isopropoxide, 15-16 Amberlite-15, 266 Amberiite IR 120, 267 Amide acetals, 527-528 Amides, 424,456 Amidines, bicyclic, 16-18 Amine oxides, 270 p-Aminoacetophenone, 18 Amino adds, 252, 273, 368 Aminoalkenylation, 95 4-Aminobenzoic add, 45 2-Amino-3-cyano-5-chloromethylpyrazine 1-oxide, 459... 

Geminal and vicinal H-H couplings have been measured by Guthrie et for new examples of 5-substituted-l-aza-4,6-dioxabicyclo[3.3.0]octanes(bicyclic amide acetals), and for some examples of the new heterocyclic system, 5-sub-stituted-l-aza-4-oxa-6-thiabicyclo[3.3.0]octanes (bicyclic amide mono-thioacetals). A detailed analysis of this data combined with the X-ray results allowed the authors to elucidate the stereochemistry and conformation of these ring systems. 

Transannular cyclization of unsaturated lactams was induced by mercury(ll) acetate, the weakly nucleophilic amidic nitrogen is the reaction center. The driving force for this cyclization is the strain of the bicyclic product, only one isomer was recovered regardless of the alkyl substituent. By reductive cleavage the bicyclic lactam, e.g., 6, was obtained in moderate to good yield125. 

The efficient catalytic cyclization (aminocarbonylation) of A-(3-hydroxy-4-pentenyl)amides and carbamates in acetic acid gave m-fused bicyclic pyrrolidine lactone compounds54,56 (Table 2), in agreement with the observed ra-directing capability of the hydroxy group in analogous electrophile mediated additions (Section 7.2.6). In tetrahydrofuran the reaction rate is unacceptably low. In methanol a competitive allylic substitution leads to 1,2,5,6-tetrahydropyridines. Furthermore, lower yields were obtained in the cyclization of the corresponding ureas. 

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