Hexahydro-l,3,5-triazines

Another versatile approach, which nicely complements these Mannich-based procedures, incorporates a preformed symmetrical hexahydro-l,3,5-triazine (HHT) intermediate. In this case the phosphorus reagent reacts with HHT as a trimeric form of the normal aldimine species generated in situ between the amine or amino acid and formaldehyde. These HHT reagents can often be puritied and isolated prior to the reaction with phosphites. They are reasonably stable under neutral or slightly basic conditions, but they can readily revert back to the original amine and formaldehyde after heating with aqueous acid (25). Several can be purchased commercially. 

Nitro-2-(nitroimino)hexahydro-l,3,5-triazine (1,4,5,6-Tetrahydro-iV,5-dinitrotriazin-2-amine)... 

JPR269>. 1,3,5-TriaIIyl-hexahydro-l,3,5-triazine has been used in the preparation of a C-4 unsubstituted azetidinone which is the starting material for the synthesis of penems and cephams <00S289>. A novel method for the preparation of AfW-disubstituted-Af"-nitroguanidines via 2-nitroimino-hexahydro-1,3,5-triazine derivatives has been studied <00TL7187>. 

The PE spectra of some cyclic triamines with the nitrogen atoms in 1,3-positions like hexahydro-l,3,5-triazines (59) and tetracyclic derivatives such as 60 and 61 have been studied and interpreted with regard to their conformational properties110. The n ionizations lead to two strongly overlapping bands between 7.5 and 9.5 eV which are consistent with diequatorial-monoaxial nitrogen substituent orientations at the hexahydro-... 

Uberwiegend in 4-Stellung werden Phenole durch l,3,5-Trialkyl-hexahydro-l,3,5-triazine als Mannich-Reagenzien aminomethyliert1. 

Im Fall von 1,3,5-Tribenzyl-hexahydro-l, 3,5-triazin erhalt man auf diese Weise mit Malonsaure-diethylester i-Benzylamino-propamdure-ethyiester (63%) neben schr wenig Hexahydropyrimidin-Derivat. 

Nitroimino-5-nitro-hexahydro-l,3,5-triazine improvised ANFO... 

Decomposition of l-methyl-2-pyrrolidinone (67) was studied by vapor-phase photolysis (72JA8281). Irradiation (Hg sensitized) led, in addition to extensive polymer formation, to the following products carbon monoxide (31%), ethene (24%), water (24%), l,3,5-trimethyl-hexahydro-l,3,5-triazine (8%), 1-methylazetidine (6%), 1-methylpyrrole, and methane (<1%). The mechanism of formation of most of these products involves... 

Hexahydro-l,3,5-triazine-2,4-dione and 4-thioxo-tetrahydro-l,3,5-triazin-2-one may be synthesized in an analogous manner (equations 42 and 43 respectively) (73ZC408). 

Alkyl-hexahydro-l,3,5-triazin-2-ones are prepared by the reaction between urea, formaldehyde and primary amines (73S243). The intermediate polycondensate (87) undergoes intramolecular cyclization on heating to yield the desired product (Scheme 52). By using substituted ureas (or thioureas) and/or different aldehydes, a wide variety of N-substituted 5-alkyl-hexahydro-l,3,5-triazin-2-ones (or 2-thiones) may be prepared. 

The reaction between aldehydes and ammonia leads to compounds usually called aldehyde ammonias (equation 80). The first reported compound ( acetaldehyde ammonia ) was synthesized by Liebig (1835LA(14)133). Nielsen et al. (73JOC3288) have shown that most of these compounds are hexahydro-l,3,5-triazines, which are usually isolated as the trihydrates (Table 17). When aldehydes containing a branched alkyl substituent are used, the free hexahydro-l,3,5-triazines may be formed (Table 17). The kinetics of the reaction between acetaldehyde and ammonia have been studied by H NMR spectroscopy (73JOC2931), and shown to be rather complex. It is beyond the scope of this review to discuss the reaction fully. 

Methylamino-methanphosphonsiiiire-diisopropylester (Hydrochlorid)341 33,2 g (0,2 mol) Phosphorigsaure-di-isopropylester werden zu 8,61 g (0,067 mol) l,3,5-Trimethyl-hexahydro-l,3,5-triazin gegeben und das Ge-misch 4 Stdn. unter Riihren auf 100-110° erhitzt. Dann wird mit Diethylether verdtinnt und das Hydrochlorid durch Einleiten von Chlorwasserstoff ausgefallt Ausbeute 35,7 g (73%) Schmp. 128-131°. 

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