Hydropyrimidines. V. Hexahydropyrimidines. The reaction of aldehydes and ketones with 1,3-diaminopropanes

1967 ◽  
Vol 20 (8) ◽  
pp. 1643 ◽  
Author(s):  
RF Evans

Hexahydropyrimidine and some N-alkylated derivatives have been obtained from the reaction of the corresponding trimethylenediamine or its monoprotonated salt with formaldehyde. A variety of spectroscopic evidence supports a cyclic structure for these compounds in preference to a tautomeric open-chain form. The chemical behaviour of hexahydropyrimidine is explicable in terms of a cyclic di-secondary amine structure. The cyclic structure is destabilized with respect to the open- chain form if the hydrogen atoms attached to C2 of the hexahydropyrimidine ring are replaced by alkyl groups and cannot be detected when, in addition, one of the hydrogen atoms attached to nitrogen is replaced by the bulkier t-butyl group. Hexahydro-2-methylpyrimidine is dehydrogenated to 1,4,5,6- tetrahydro-2-methylpyrimidine on shaking with Adams catalyst and hydrogen under laboratory conditions. Hexahydropyrimidines which are tautomeric mixtures are reduced to the corresponding N-alkyl-1,3- diaminopropanes, while those possessing cyclic structures are inert.

1977 ◽  
Vol 252 (10) ◽  
pp. 3486-3492
Author(s):  
C F Midelfort ◽  
R K Gupta ◽  
H P Meloche
Keyword(s):  

1963 ◽  
Vol 41 (11) ◽  
pp. 2800-2806 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold

The relative rates of reaction of a large number of ortho-alkyl phenols with styrylperoxy radicals have been measured at 65 °C. These groups have both an accelerating effect owing to their electron-donating character and a retarding effect which arises from steric factors. With two ortho-alkyl groups both the reaction rate and the overall polar contribution to the transition state decrease as the size of the alkyl groups is increased. A single o-t-butyl group produces a small enhancement of the reaction rate over and above its polar effect but this is not observed with any other alkyl groups.


1958 ◽  
Vol 36 (3) ◽  
pp. 480-485 ◽  
Author(s):  
P. A. J. Gorin ◽  
A. S. Perlin

Naturally-occurring apiose is shown by synthesis to be the D-isomer in the open-chain form. In this synthesis 3-O-benzyl-D-fructose is cyanohydrated and the resulting heptonic lactones are reduced to 3-O-benzyl-2-C-(hydroxymethyl)-D-arabo-hexitol. The latter is oxidized with lead tetraacetate affording 2-O-benzyl-3-C-(hydroxymethyl)-D-glycero-tetrose which, on debenzylation, gives 3-C-(hydroxymethyl)-D-glycero-tetrose (D-apiose).


IUCrData ◽  
2016 ◽  
Vol 1 (9) ◽  
Author(s):  
Jason A. Jordon ◽  
Jeanese C. Badenock ◽  
Gordon W. Gribble ◽  
Manpreet Kaur ◽  
Jerry P. Jasinski

In the title molecule, C16H19NO2, all the non-hydrogen atoms except two of the C atoms of thetert-butyl group lie on a crystallographic mirror plane. No classical hydrogen bonds are observed. The crystal packing is influenced by weak π–π and C—H...π interactions.


2016 ◽  
Vol 62 ◽  
pp. 277-298
Author(s):  
G. Jeffery Leigh ◽  
John F. Nixon

Michael Lappert was one of the giants of twentieth-century organometallic chemistry. His research, carried out over six decades and leading to about 800 publications, had a profound and influential effect on the field, and his contributions covered almost every block of the Periodic Table. His early reputation was established by his extensive studies in boron chemistry exemplified by the reports of BCl 4 − , BN cyclobutadiene analogues, triborylamines, BCl 3 -catalysed ortho -Claisen rearrangements and evidence for restricted rotation about the B–N bond in aminoboranes. He had a lifelong interest in amides, including those of carbon, and especially electron-rich olefins, which remarkably were the ready source of numerous transition-metal carbene complexes. The last could also be obtained directly from the Vilsmeier reagent. He was the first to show that a carbene complex may act as an initiator of olefin metathesis. Later interests concerned the syntheses of new types of compound from all blocks of the Periodic Table driven by his imaginative use of new types of ligand (either sterically crowded or having no β-hydrogen atoms, often including SiMe 3 or Bu t substituents to confer lipophilicity). The use of CH n SiMe (3− n ) ( n = 0, 1 or 2) to stabilize transition-metal alkyl compounds was a major advance, because at the time stable homoleptic (a term he introduced) transition-metal alkyl compounds were unknown. He showed that the −CH(SiMe 3 ) 2 ligand could stabilize both low-coordinate transition metal and lanthanide compounds. Similarly, carbene analogues of the Main Group 14 elements germanium, tin and lead were obtained. Surprisingly in the solid state, these species were weakly dimerized (for example R 2 Sn=SnR 2 ), and unexpectedly exhibited a pyramidalized geometry at the heavy element. The latter had very significant bonding implications, because it differed fundamentally from the well-known planar structure of the corresponding alkenes. The first persistent or stable paramagnetic heavier Main Group element species MR 2 (M = P or As) and MR 3 (M = Ge or Sn) were also obtained while parallel work using −N(SiMe 3 ) 2 resulted in the corresponding Main Group amido derivatives. Other lipophilic ligands, such as β-diketiminates, were also widely used, as were bulky aryloxo and thiolato ligands, to obtain stable low-coordinate Main Group species. The first examples of d- and f-block species containing bridging alkyl groups were described. Those who worked with him cited his vast knowledge and supportive low-key advisory style, which ensured a contented and productive laboratory atmosphere. In addition to his scientific work, he was deeply interested in opera, literature and the theatre, about which he could talk knowledgeably.


Synlett ◽  
2020 ◽  
Vol 31 (04) ◽  
pp. 343-348
Author(s):  
Vladimir S. Moshkin ◽  
Evgeniya V. Gorbunova ◽  
Evgeny M. Buev ◽  
Vyacheslav Y. Sosnovskikh

Aliphatic aldehydes readily react with nonstabilized azomethine ylides in one of the three ways to give oxazolidines, pyrrolidines, or Mannich bases, depending on the structure of the starting compound and the reaction conditions. The use of N-(methoxymethyl)-N-[(trimethylsilyl)methyl]benzylamine in DMF provided 5-alkyloxazolidines in 40–97% yields. On the other hand, three-component reactions of aliphatic aldehydes bearing one α-hydrogen with N-methyl(benzyl)glycine and formaldehyde gives Mannich bases in yields of 47–98%. A similar reaction of aldehydes bearing branched alkyl groups and two hydrogen atoms at the α-position proceeds as a domino process that gives 3-alkyl-3-formylpyrrolidines in yields of 34–93%.


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