Suffixes cyclic compounds

Complex cyclic compounds may be named by adding the suffix -amine or the prefix amino- (or aminoalkyl-) to the name of the parent compound. Thus three names are permissible for... 

When the suffixes a7nea.nd -eneshow up in a compound name like decane or decene they are usually consistent with the alkane and alkene definitions, but not always. Benzene is a cyclic aromatic hydrocarbon, not a straight chain molecule naphthenes are cyclic compounds. 

Ketones. Acyclic ketones are named (1) by adding the suffix -one to the name of the hydrocarbon forming the principal chain or (2) by citing the names of the radicals R1 and R2 followed by the word ketone. In addition to the preceding nomenclature, acyclic monoacyl derivatives of cyclic compounds may be named (3) by prefixing the name of the acyl group to the name of the cyclic compound. For example,... 

Chlorocyclopentanecarboxylic acid (In similar fashion to the use of the -carbaldehyde suffix in naming aldehydes, cyclic compounds with the carboxy group attached to the ring use the name of the ring with the suffix -carboxylic acid.)... 

The suffix a can be added to the stem of the substituent (giving stanna) and used to indicate replacement of carbon. This is most useful with cyclic compounds, thus cyclo-(CH2)5SnMe2 is 1,1-dimethylstannacyclohexane. Doubly bonded compounds are similarly named as alkenes with one or two of the doubly-bonded atoms replaced by tin the compound R2Sn=CR2 is a stannene, and iUSrwSnfU is a distannene. 

If the same number for the functional group suffix is obtained in both directions, the chain is numbered in the direction that gives a substituent the lowest possible number. Notice that a number is not needed to designate the position of a functional group suffix in a cyclic compound, because it is assumed to be at the... 

Monoterpenoid ketones are cyclic compounds in which a carbonyl group is bonded to two carbon atoms. They are produced by oxidation of alcohols and are relatively stable molecules. Monocyclic ketones such as pulegone contain a single carbon ring while bicyclic ketones like camphor contain two fused rings. Most ketones have the suffix one . 

For linear diterpenes or the linear segments of cyclic compounds with ambiguous double bond stereochemistries, the steric relationship about the double bond is indicated by a Z or E suffix (e.g., 13(14)E, 2(3)Z). The Z or E assignment results from the comparison of the sequence-rule-preference of the four atoms attached to the doubly bonded carbons (as specified in Rule E-2.2. of the lUPAC Rules for Nomenclature of Organic Chemistry). Several examples of Z and E assignment are discussed below in order to familiarize the reader with this method. 

Acyclic nitriles are named by adding -nitrile as a suffix to the alkane name that includes the carbon atom of the nitrile. The carbon atom of the nitrile is C-1. Cyclic compounds with the —CN group bonded to the ring are named using the suffix -carbonitrile. The ring carbon bearing the cyano group is C-1, but that number is not included in the name. 

The common method of naming aldehydes corresponds very closely to that of the related acids (see Carboxylic acids), in that the term aldehyde is added to the base name of the acid. For example, formaldehyde (qv) comes from formic acid, acetaldehyde (qv) from acetic acid, and butyraldehyde (qv) from butyric acid. If the compound contains more than two aldehyde groups, or is cyclic, the name is formed using carbaldehyde to indicate the functionality. The IUPAC system of aldehyde nomenclature drops the final e from the name of the parent acyclic hydrocarbon and adds al. If two aldehyde functional groups are present, the suffix - dial is used The prefix formyl is used with polyfunctional compounds. Examples of nomenclature types are shown in Table 1. 

One of the invariant amino acids is a unique P-amino acid called Adda (2S,3S,8S,9S)-3 amino-9 methoxy-2,6,8-trimethyl-10-phei5fldeca-4,6-dienoic acid is the most unusual structure in this group of cyanobacterial cyclic peptide toxins). A two-letter suffix (XY) is ascribed to each individual toxin to denote the two variant amino acids (Carmichael 1988). X is commonly leucine, arginine, or tyrosine. Y is arginine, alanine, or methionine. Variants of all the invarianf amino acids have now been reported, e.g., desmethyl amino acids and/or replacement of the 9-methoxy group of Adda by an acetyl moiety. Currently there are in excess of 60 variants of microcystin that have been characterized (Rinehart 1994 Sivonen and Jones 1999). Of these 60 compounds, microcystin-LR would appear to be the microcystin most commonly found in cyanobacteria. It is also common for more than one microcystin to be found in a particular strain of cyanobacterium (Namikoshi 1992 Lawton 1995). The microcystin variants may also differ in toxicity (Carmichael 1993). The literature indicates that hepatotoxic blooms ofM aeruginosa containing microcystins occur commonly worldwide. 

Studies in several laboratories have shown that strongly hepatotoxic cyclic heptapeptides of a common type occur in different strains of Microcystis [59]. Microcystis aeruginosa, the species most frequently investigated contains the peptide formulated in Fig. 25. The two letter suffix LA designates the two L-amino acids in positions 2 and 4 (X, Y = Leu, Ala) which have been found variable in all of the toxins examined to date. X can also be arginine (R) or methionine (M). The 10-carbon chain jS-amino acid is unique for this type of hepatotoxic compound. Another not quite common structural element is the unsaturated side chain of dehydroalanine (No. 7), the formation of which can readily be imagined by elimination of H2O from serine or H2S from cysteine. 

Cyclic ketones have the carbonyl carbon as part of a ring. The nomenclature is straightforward in that cycle is used to denote the ring, the usual prefix is used to indicate the number of carbons in the ring (including the carbonyl carbon), and the suffix is one. Compound 8 is named cycloheptanone. There is no need to use the number 1, as in 1-cycloheptanone, because the carbonyl carbon must receive the lowest possible number. When there is a substituent, as in 9, the carbonyl carbon is always Cl, so, again, there is no need to use 1. Therefore, 9 is 3-chlorocyclopentanone. The use of a number to indicate the position of the carbonyl is essential in acyclic ketones such as 6 or 7, but unnecessary in cyclic ketones such as 8 or 9. 

All esters discussed so far are acyclic molecules (this means they do not contain rings), but there are also cyclic esters, where both the acyl carbon and the alcohol oxygen are constituent members of a ring, as in 88-90. These cyclic esters are called lactones. The common names for structurally simple lactones arise by using the suffix for the open chain carboxylic acid precursor and the word lactone. Compound 88 is y-butyrolactone and 89 is 6-valerolactone, where the name is taken from the common names for the four-carbon acid (butyric acid) and the five-carbon acid (valeric acid). The lUPAC names are based on the cyclic ether, so 88 is 2-oxoolane and 89 is 2-oxooxane. 

Cyclic esters are called lactones. The lUPAC system has developed a set of rules for naming these compounds. Nonetheless, the simplest lactones are still named by dropping the suffix -ic acid or -ok acid from the name of the parent carboxylic acid and adding the suffix -olactone. The location of the oxygen atom in the ring is indicated by a number if the lUPAC name of the acid is used or by the Greek letter a, j3, y, 8, e, and so forth, if the common name of the acid is used. 

If the C atoms in an alkane are bonded in a row with a formula of the form CH3(CH2)mCH3, the compound, called an unbranched alkane, is named according to the number of C atoms present. All are named with a stem name and the suffix -ane. A cyclic (ring) alkane has the general formula (CH2)m and is designated by the prefix cyclo-. 

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