Coniine, structure

Coniine, C H N. is the toxic principle of the poison hemlock drunk by Socrates. When subjected to Hofmann elimination, coniine yields 5-(iV,N-dimethylamino)-l-octene. If coniine is a secondary amine, what is its structure ... 

Coniine, molecular model of. 28 structure of, 294 Conjugate acid, 49 Conjugate base, 49 Conjugate carbonyl addition reaction, 725-729 amines and, 727 enamines and, 897-898 Gilman reagents and, 728-729 mechanism of, 725-726 Michael reactions and, 894-895 water and. 727 Conjugated diene, 482... 

As shown in Table I, this reaction sequence has wide generality and is readily applicable to the straightforward synthesis of various naturally occurring alkaloids such as coniine,9 pumiliotoxin C,11 1 and solenopsin A and B.11 Oxime sulfonates of either linear or cyclic structures may be used. Obviously, the regioselectivity of the reaction follows the general rule of... 

The data shown in Table 2 illustrate the general paucity of comparative toxicity data within an isosteric series of chemicals. In this Table a variety of toxic end-points observed for benzene and naphthalene have been compared with those of their simple heterocyclic analogues, and it is clear that it is almost impossible to derive chemical structure-biological activity relationships from the published literature for even such a simple series of compounds. Even basic estimates of mammalian toxicity such as LD50 values cannot be accurately compared due either to the absence of relevant data or the noncomparability of those available. Thus in a field where there are little comparative data on the relative toxicity to mammals of pyrrole, thiophene and furan for example, it is difficult to relate chemical structure to biological activity in historical heterocyclic poisons such as strychnine (3) and hemlock [active agent coniine (4)]. 

R = H), and coniine (12) were isolated (16) (Table 1). But, because the science was young and the materials complex, it was not until 1870 diat die structure of the relatively simple base coniine (12) was established (17) and not until 1886 that the racemic material was synthesized (18). The correct structure for strychnine (13, R = H) was not confirmed by x-ray crystallography until 1956 (19) and the synthesis was completed in 1963 (20). 

Piperidine alkaloid toxins, such as coniine, are structurally similar to nicotine, and contained in all parts of the plant. 

The photolyses of 2-aziadamantane (16) within CyD hosts give product distributions that largely depend on the type of CyD and thus the supramolecular structure. The formation of 2,4-didehydroadamantane (22) is essentially precluded when other inter- and innermolecular reaction channels are available. However, the formation of 22 is greatly enhanced within supramolecular coniines. The amount of reduction to hydrocarbon 2, the share of azine 19 and 2-adamantanone, the formation of CyD ethers 25a and 25b, and the insertion into solvent molecules yielding 25c-e can widely be controlled by geometry and composition of the ICs. This very interesting influence of the host as mediator can be observed especially well for the photolyses of 16, which primarily yield carbene 21—a species that has no intramolecular pathways to stabilization. 

Thus, all possibilities of structural elucidation may be shown with MS/MS. Quantitative analysis is another aspect, developed by Cooks and co-workers [189a,c], using Cl. In samples of hemlock Conium maculatum L.) they demonstrated the presence of coniine by collisional analysis of protonated molecular ions (m/z 128). 

Plants of many genera produce compounds called alkaloids (alkali-like), and indeed all the thousands of known alkaloids contain nitrogen, by definition, and most are basic, and many are also toxic. Nicotine, a structurally simple example of an alkaloid, is a highly toxic substance, and is the major active component in tobacco (Nicotiam sp.), and amongst the most addictive drugs - an extraordinary contrast to the vital role in life played by nicotinic acid amide (32.2.1). Coniine, the active ingredient of hemlock (Conium maculatum), is another stmcturally simple example. 

Although structurally very similar to pelletierine (16) the hemlock alkaloid coniine (17) is notably of quite different origins, arising as it does from acetate in a fairly well understood pathway. 

Since conhydrine differs from coniine by containing one oxygen atom and since it can be transformed into an iodoconhydrine convertible by reduction to Z-coniine (165, 174, 175), the base is a hydroxyconiine (130). Structural formulas have been suggested for conhydrine such as (CVIII) (176) containing a quaternary C-atom and (CIX) which is a-propyl-y-... 

Other alkaloids were extracted soon after. Brucine (1819), pipeline (1819), caffeine (1819), colchicine (1820) and coniine (1826), codeine (1832), atropine (1833), papaverine (1848), " were subsequently obtained. These first isolations were coincidental with the advent of the percolation process for the extraction of drugs. Coniine was the first alkaloid to have its structure established (Schiff, 1870) and to be synthesized, but for others, such as colchicine, it was well over a century before the structures were finally elucidated. 

A color test utilizing isatin for piperidine and pyrrolidine alkaloids containing the structural unit — NH—CH2—CH2— has been described (53). Coniine and conhydrine give a positive test but pseudoconhydrine, which lacks the above feature, does not. The Conium alkaloids have been separated by gas-liquid chromatography (54). 

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