N-allyl amide

It is interesting to contrast these double lithiations of secondary N-allyl amides with the double lithiation of a secondary N-silyl amine 59, which leads to vinylic y-lithiation, rather than allylic a-lithiation.41 42 The product 60 cyclises onto carbonyl electrophiles to yield pyrroles such as 61. 

CsH9Cl4NOTe Tellnrate(IV) [(2-Methyl-4,5-dihydro-1,3-oxazolium-5-yl)-methyl]-tetrachlor- E12b, 360 (TeCl4 4- N-Allyl —amide)... 

Isomerization of N-allyl amide to N-propenyl amide is a key step of the deprotection of an amino group. ( )-N-Aryl-N-(l-propenyl)ethanamides 35 are obtained via the double bond migration of N-aryl-N-allylamide 34 catalyzed by a ruthenium hydride complex [19]. The configuration of the N-propenyl moiety in the product is almost E, and the high E selectivity is probably due to the steric repulsion between the aryl group and the methyl substituent of the propenyl group (Eq. 12.13). 

In contrast to the well-investigated chelation controlled ester enolate Claisen rear-rangments, the corresponding rearrangement of N-allylated amides is much less appUed. Tsunoda et al. evaluated the synthetical potential of N-crotyl glycolamides and glycinamides 215 [125] and the results obtained are listed in Table 5.2.23. 

Metathesis of N-tosylated ene-amides and yne-amides has been less extensively investigated. An example of the RCM of ene-amides is a new indole synthesis developed by Nishida [79] metathesis precursor 96 (prepared by ruthenium-catalyzed isomerization of the corresponding allyl amide) is cy-clized to indole 97 in the presence of 56d (Eq. 13). 

New organocatalysts prepared by the Jacobsen group showed that alkylation of the final amide bond increased the enantioselection (Scheme 38, compare R2 = Me, 98% ee to R2 = H, 91% ee). Thus, the reaction performed with N-allyl benzaldimine and with the dimethylamide-ending thiourea (Scheme 38 with Ri = R2 = Me) gave up to 99% ee. This compound is a structural analogue of the urea depicted in Scheme 36 [148,152,154]. 

The directive effect of allylic hydroxy groups can be used in conjunction with chiral catalysts to achieve enantioselective cyclopropanation. The chiral ligand used is a boronate ester derived from the (VjA jA N -tetramethyl amide of tartaric acid.186 Similar results are obtained using the potassium alkoxide, again indicating the Lewis base character of the directive effect. 

Zur Herstellung von 1,2-Diamino-propanen in hoher Ausbeute eignet sich die Ami-nomercurierung-Demercurierung von N-Allyl-acetamid mit Anilin oder substituierten Anilinen, gefolgt von Hydrolyse der Amid-Gruppierung2 ... 

The elegant asymmetrization methodology of a meso compound, achieved in high enantioexcess under chiral environment, was the highlight of the total synthesis of (+)-pancratistatin (94) reported by Trost and Pulley (31]. The synthesis commenced with ( )-conduritol-A (130), obtained from p-benzoquinone, (Scheme 18) which was converted into the acetonide 131 and thence, via the dialkoxide to the cis-bis carbonate 132 (Scheme 19). The chiral n-ailyl palladium complex A formed on treatment erf 132 with the catalyst generated from chiral bis-amide 133 and n-allyl palladium chloride underwent azide substitution from the less hindered face of the molecule to provide the monocarbonate 134 in excellent yield and with high optical induction. 

In the indole alkaloid arena, the general rules of radical cyclizations apply. For example, radical cyclization via the 5-endo-trig mode is usually disfavored unless the substrate possesses a structural setup (e.g. N,N-disubstituted amides, but not N-phenyl or N-allyl [17d]) that conformationally favors the 5-endo-trig mode. Radical cyclizations via the 5-endo-trig mode do occur for some substrates, such as 1,3, and 7. 

Some examples of photolytic intramolecular [2 + 2] cycloadditions which lead to the formation of lactones and lactams are sketched in Scheme 9.9. The allyl ester and N-monosubstituted amide do not undergo cydization, probably because of the high energy of the required E conformers. Cydization of the homoallyl ester does,... 

Fig. 28 Nickel-catalyzed cyclization of N-allyl a-bromo amides...

With A-benzyl or A-allyl amides, the a-lithiated products are more stable. N,N-dibenzylbenzamide 48, for example, is a-lithiated with LDA to give 49 and hence 50,38 while two equivalents of BuLi or LDA are sufficient toa-lithiate the secondary amides 51 and 54 to give 52 or 55 which react with electrophiles to produce 53 and 56.39 The lithiated A-Boc allyl amides 57 react with selectivity which is highly electrophile dependent, but transmetallation of 58 to the allylzinc reagent leads to good a-selectivity.40... 

N-Allyl tertiary amides 72 can be lithiated with r-BuLi and, like the secondary amides 54 and 57 they react y to nitrogen to give cis acylenamine products 74, with the intermediate organolithium adopting a structure approximating to 72.152 The stereochemistry of the reactions of lithiated allyl amides and carbamates in the presence of (-)-sparteine53 is discussed further in chapter 6. 

Allylic amidation Nitrosocarbonylmethane undergoes an ene reaction with various olefins to form allylic N-hydroxy amides, often in useful yields. 

Tellurate(IV) [(3-Allyl-2-methyl-4,5-dihydro-l,3-oxazolium-5-yi)-methyl]-tetrachlor E12b, 360 (TeCl4 + N,N-Diallyl-amide)... 

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