3.8- Diazabicyclo octane synthesis

For the synthesis of 18 trichlorophosphine is alkylated to dichloro[bis(tri-methylsilyl)methyl]phosphine by means of the appropriate Grignard reagent. The subsequent elimination of HC1 can be achieved with, for example, diazabicyclo-octane (DABCO), however, the use of triethylamine is advantageous for the work-up.37,38... 

Details are given of the synthesis of new methacrylate monomers containing pendant quaternary ammortirrm moieties based on diazabicyclo-octane. The monomers were homopolymers using azobismethylpropionarrride dihydrochloride as initiator. The monomers and polymers were characterised by elemental analysis, TGA, DSC, FTIR and carbon 13 NMR. Antimicrobial activities were investigated against S.aureus and E.coli. 41 refs. 

We note further studies concerning the ethanolysis of l-chloro-2-aza-adamantanes, the rearrangement " of iV-chloro-tropanes, the dealkylation " of (76) with PhSeH, the formation of a stable adduct between (77) and sulphur dioxide " and also between aaa-trifluoroacetophenone and 1,4-diazabicyclo-octane, "" and the use of (78) as an intermediate " in the synthesis of the antifungal antibiotic aristeromycin (79), which is a carbocyclic analogue of adenosine. The acid-catalysed cyclization "" of (80) gave (81) the structure of the product was determined by X-ray analysis. 

Zeolite Beta is normally prepared at high alkaline pH with a templating mixture of Et4N and Na cations which in addition are not specific for this structure [72]. This synthesis can also be carried out in F" medium H = 7-10) with diazabicyclo-octane (DABCO) [73]. While with OH" anions the size of the crystals is generally below about 0.5 pm, in the presence of F" anions and without alkali cations, crystals have a pseudo octahedral morphology with a size up to 10 im(Figure 33.). 

Treatment of the Z-aldehyde 9 (R1 = R2 = H) with trifluoroacetic acid in dichloromethane at — 10 C, then with l,4-diazabicyclo[2.2.2]octane or /V,/V-diethylpyridin-4-amine, constitutes the first synthesis of 27/-azepine (10, R1 = R2 = H) which was isolated, with great difficulty and in very low yield (1 %), as a highly volatile, unstable oil, the structure of which was confirmed by high field H and 13CNMR spectroscopy.290 Similar treatment of the Z-alkenones 9a-d furnishes the thermally unstable (5)-2/7-azepines lOa-d in much higher yields.291... 

FIGURE 8.15 Alkylamines encountered in peptide synthesis. 1, pyridine 2, 2,4,6-trimethylpy-ridine 3, 2,6-di-ferf-butyl-4-methylpyridine 4, 4-dimethylaminopyridine 5, A-methyl-morpholine, 6, fV-methylpiperidine 7, triethylamine 8, diisopropylethylamine 9, l-diethylaminopropane-2-ol 10, dicyclohexylamine 11, diethylamine 12, piperidine 13, piperazine 14, morpholine 15, l,8-diazabicyclo[5.4.0]undec-7-ene 16, 4-(aminoethyl)piperidine 17, frw(2-aminoethyl)amine 18, 3-dimethylaminopropylamine 19, methylamine 20, dimethy-laminoethane-2-ol 21, 1,2,2,6,6-pentamethylpiperidine 22, l,4-diazabicyclo[2,2,2]octane 23, 7-methyl-1,5,7-triazabicyclo[4,4,0]dec-5 -ene. 

Figure 8.25 Solid-solid or solid-vapour synthesis of a hydrogen bonded co-crystal between ferrocene dicarboxylic acid and 1,4-diazabicyclo [2.2.2] octane (reproduced by permission of The Royal Society of Chemistry).

Synthesis. Ammonium sulfite monohydrate, 4,4 -bipyridyl, 1,4-diazabicyclo[2.2.2]octane (DABCO), neodymium(III) nitrate hexahy-drate (Aldrich), 1,10-phenanthroline, ethylenediamine (SD Fine, India), and zinc acetate dihydrate (Qualigens, India) of high purity were used for the synthesis. 

Lehn reported the synthesis and solid-state architecture of chiral 2,5-diazabicyclo[2.2.2]octane-3,6-dione. The racemic material adopted an infinite chain of alternating (+) and (-) units, whereas the single enantiomer formed a cyclic tetrameric structure (Fig. 11.14) [49]. 

Subjection of this material to a formylation protocol involving a Rh catalyst, a bulky phosphite and DABCO (l,4-diazabicyclo[2.2.2]octane) in the presence of H2/CO gas mixture, gives a high yield of the desired aldehyde. Iteration of these steps leads to the synthesis of Tolypothrix pentaether. 

Decomplexation of the P(III) moiety of the boronhydride complex (10) by the base l,4-diazabicyclo[2.2.2]octane (DABCO) followed by an internal Staudin-ger reaction has been reported to yield the linear polymer (12). Hyperbranched polymers are obtained by using the same procedure but starting from the diphosphine (13). Treatment of (11) with NaNs leads to an intramolecular Staudinger polycondensation affording polymer (12) as well. Compound (13) has proven to be a useful starting material for the synthesis of dendrimers with phosphine end groups. ... 

Construction and synthesis of ribonucleases based on l,4-diazabicyclo[2.2.2] octane and imidazole 02IZV1014. 

The fundamental idea of sterically restricted cis-fused 5-membered bicyclic structure as an efficient chiral environment for enhanced asymmetric induction was extended to the synthesis of several synthetically useful, optically active aldehydes. The reaction of aminals (l,3-diazabicyclo[3.3.0] octane derivatives) having a fixed cis-fused 5-membered bicyclic ring structure, obtained from the diamine la and appropriate aldehydes, with nucleophiles was investigated. Several functionalized aldehydes were obtained in high e.e. and successfully applied to the synthesis of selected optically active natural products. 

CarbocycUc Steroids.— The Torgov synthesis continues to exhibit its great versatility and was recently employed in the first synthesis of B-homo-oestrone. Condensation of the vinyl alcohol (407) and 2-methy 1-cyclopentane-l,3-dione in the presence of l,4-diazabicyclo[2,2 ]octane and cyclisation with toluene-p-sulphonic acid gave the B-homo-oestrapentaene (409) in 33 % overall yield from 3-methoxybenzosuberone. A three-stage reduction by sodium borohydride, catalytic hydrogenation, and lithium-ammonia afforded 3-methoxy-B-homo-... 

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