Bases 1,5-Diazabicyclo nonene

The elimination of HX from an alkyl halide is a very general reaction and can be accomplished with chlorides, fluorides, bromides, and iodides.232 Hot alcoholic KOH is the most frequently used base, though stronger bases233 (OR, NH2", etc.) or weaker ones (e.g., amines) are used where warranted.234 The bicyclic amidines l,5-diazabicyc o[3.4.0]nonene-5 (DBN)235 and l,8-diazabicyclo[5.4.0]undecene-7 (DBU)236 are good reagents for difficult cases.237... 

Two frequently used amidine bases are DBN (l,5-diazabicyclo[3.4.0]nonene-5) and DBU (l,8-cfiazafciicyclo[5.4.0]undecene-7). 

Chapter S you met the bases DBU (l,8 diazabicyclo[5.4.0]undecene-7) and DBN (l,5-diazabicycio[3.4.0]nonene-5) named in the same way—and you will meet them again in the very next chapter, as they are particularly good bases for the promotion of elimination reactions. 

Methyl acrylates." The reagent is converted by LDA into the stable ester enolate a, which is alkylated by primary alkyl iodides and allylic bromides in the presence of HMPT to give the useful Mannich bases 2. These products can be converted into methyl acrylates (4) by quaternization (quantitative) followed by treatment with diazabicyclo[4.3.0]nonene-5 (DBN) in refluxing benzene. 

BASES Ascarite. Barium hydroxide. 1,8-Bis(dimethylamino)naphthaIene. n-Butyl-amine. I, S-Diazabicyclo 4.3.0]nonene-5 (DBN). l,4-Diazabicydo 2.2.2]octane-... 

Standard base triethylamine105 in some cases improved yields with l,5-diazabicyclo[4.3.0]-5-nonene (H. Wamhoff, A. Bohle, and R. Luttgens, unpublished results). 

Bases Alumina, see p-Toluenesulfonylhydrazine. Dehydroabietylamine. 1,5-Diazabicyclo [4.3.0]nonene-5. 1,4-Diazabicyclo[2.2.2]octane. l,S-Diazabicyclot5.4.0]undecene-5. 2,6-Di-/-butylpyridine. N,N,-Diethylglycine ethyl ester, see /-Amyl chloroformate. 2,6-Dimethyl-piperidine. Ethanolamine. Lithium diisopropylamide, see Diphenylsulfonium isopropylide. Lithium nitride. Magnesium methoxide. N-Methylmorpholine. Piperidine. Potassium amide. Potassium hydroxide. Potassium triethylmethoxide. Pyridine. Pyrrolidine. Sodium methoxide. Sodium 2-methyl-2-butoxide. Sodium thiophenoxide. Thallous ethoxide. Triethyla-mine. Triphenylphosphine, see l-Methyl-2-pyrrolidone. 

Diazabicyclo[4.3.0]nonene-based peptidomimetics with a quaternary chiral centre are prepared via intramolecular condensation of A -aminopropyl-y-lactam [27]. Reductive amination of oxazolidinone aldehydes with A -monoprotected propylenediamine give A -phthalimidopropyl lactams however, trials of cyclization to bicyclic amidines after deprotection under dehydration conditions are unsuccessful. To solve this problem, the phthalimides are converted to thiolactams with Lawesson reagent. Deprotection followed by treatment with mercury (11) chloride (HgCl2) yields desired cyclic amidines (Scheme 3.14). 

Hutton, C.A. and Bartlett, RA. (2007) Preparation of diazabicyclo[4.3.0]nonene-based peptidomimetics. The Journal of Organic Chemistry, 72, 6865-6872. 

S -p-Fluorosulfonylbenzoyladenosine. The 3 -FSBA is prepared by reaction of adenosine with p-fluorosulfonylbenzoyl chloride in the presence of the base, 1,5 diazabicyclo [3.4.0] nonene-5, to accept the mole of HCl from the reaction of the acid chloride with the alcohol, in a modification of the procedure of Pal, Wechter, and Colman. The initial crude product is a mixture in which 3 -FSBA predominates substantial amounts of 5 -FSBA as well as smaller amounts of 2, 3 -bis-p-fluorosulfonylbenzoyl-adenosine and 2, 3, 5 -Tris-p-fluorosulfonylbenzoyladenosine are also detected. The 3 -FSBA is purified from the mbcture. A typical preparation is as follows Adenosine (0.80 g, 3 mmoles) is dissolved in 15 ml of dimethylformamide and 1,5-diazabicyclo [3.4.0] nonene-5 (0.37 g, 3 mmoles) is added. After the mixture has been stirred for 2 hr at room temperature. 

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