1.5- diazabicyclo decanes

Studies directed toward the synthesis of bicyclomycin have resulted in the discovery of efficient routes to the construction of the 2-oxa-8,10-diazabicyclo[4.2.2]decane system (160). Thus, the monolactim ether (155) with a hydroxypropyl side chain at position 3, on oxidation with 2,3-dichloro-5,6-dicyano-l,4-benzoquinone (DDQ), gave the product (156) in good yield, presumably via an iminium species (Scheme 51). No trace of the spiro compound (157) could be detected in this reaction. The formation of (156) is probably kinetically controlled. Prior protection of the alcohol as a silyl ether, followed by DDQ oxidation, gave the pyrazinone (158) subsequent deprotection and acid treatment gave the thermodynamically preferred spiro compound (159). The method has been extended to the synthesis of (160), having an exocyclic methylene this compound is a key intermediate in the total synthesis of bicyclomycin [88JCS(P1)2585]. 

C-NMR spectra were used to obtain further conformation equilibria in the hexahydropyridazine series. In the case of the two isomeric 1,2,3,6-tetramethylhexahydropyridazines only ae conformations 245 and 246 are detected,250 and the l,6-diazabicyclo[4.4.0]decane strongly favors the ee conformation 247 [AG° 49 trans cis > 2.4 kcal mol-1].250 These results have been confirmed by photoelectron spectroscopy.152 The favoring of the... 

In the bicyclic systems AG values are greater than in the monocyclic analogs (e.g., AG 14.43 kcal mol 1) for the ae ee process in trans-2,5-dimethyl-l,6-diazabicyclo[4.4.0]decane, (depicted in Table XIX) inasmuch as nitrogen inversion and ring inversion are now coupled processes. 

The switching of a switchable solvent (a) Reversible protonation of 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) in the presence of an alcohol and carbon dioxide, (b) Polarity switching in reaction (a), (c) Miscibility of decane with the alcohol-DBU mixture (non-polar) under nitrogen and separation of decane from the ionic liquid (polar) under carbon dioxide. [Reprinted with permission from Nature 2005, 436, 1102. Copyright 2005 Nature Publishing Group.]... 

Hydroxy>3-meihyleneirldecan-2-one (2). A solution ol decanal 1 (3.12 g. 20 mmol), methyl vinyl ketone 2 (1.4 g, 20 mmol) and 1.4-diazabicyclo-octane (DABCO) (0 33 g. 

A number of substituted l,it-diazabicyclo [ t. t.O]decanes have been synthesized and shown to lower the blood pressure of 5,5-dial3ylbarblturic acid - anesthetized cats upon intravenous administration. It appears that the hypotensive... 

Only saturated derivatives of this heterocycle are known, and they have been named as l-oxa-7,10-diazabicyclo[4.4.0]decanes, numbered as in formula 1. 

Similarly 1,6-diazacyclodecane was prepared by condensation of 4-chlorobutanal with 1,4-diaminobutane to give l,6-diazabicyclo[5.3.0]decane, followed by reductive cleavage using one equivalent of BuLi and an excess of dibal-H <88CC1528>. 

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