Lead compounds functional groups

Of particular interest for shape-selective catalysis is the modification of the zeolite by means of cation exchange as well as the modification of the inner and/or outer crystallite structure by a treatment with chemically reacting agents which leads to a deposition of additional functional groups or compounds. This can be done either in the gas phase (i.c. chemical vapor deposition (CVD)) or in the liquid phase. 

Oxidized samples of nanodiamond carry many polar functional groups leading to a preferred interaction with polar compounds. The bonding is achieved via... 

Metathesis of olefins containing functional groups leads to synthesis of many valuable compounds. However, such olefins undergo metathesis with difficulty. Therefore, examples of metathesis of functionalized olefins are scarce. This is due to the following reasons (1) functional groups may react with the catalyst in some cases, they may cause its decomposition and (2) competitive complexation of functional groups rather than C = C bonds may take place. 

It is obvious that more than one functional group may be attached to a benzene ring. In some cases, the presence of two or more functional groups leads to a special name for that compound. One such case occurs when an benzene ring contains two hydroxyl groups. Each of these compounds has an lUPAC name based on the rules just discussed, but many have a unique common name. The ortho compound (34) is named 1,2-benzenediol, but its common name is catechol. The meta compound is named 1,3-benzenediol (resorcinol) and the para compound is named 1,4-benzenediol (hydroquinone). 

Compound 58 clearly offers more possibilities for disconnection. Disconnections are available at or near the carbon atom bearing the OH group, but also at or near both carbonyl carbons. The larger number of functional groups leads to more choices. Does the chemistry of the alcohol, the aldehyde, or the ketone offer the best choice for a disconnection The chemistry of alcohols is associated with oxidation and reduction (Chapter 17, Section 17.2 Chapter 19, Sections 19.2,19.3.4,19.4.1), formation and reactions of alkoxides as nucleophiles (Chapter 11, Section 11.3.2) and as bases (Chapter 12, Section 12.1), and formation of esters (Chapter 20, Section 20.5). Alcohols are converted to alkyl halides (Chapter 11, Section 11.7). Aldehydes and ketones are formed by the oxidation of alcohols (Chapter 17, Section 17.2), are reduced to alcohols (Chapter 19, Sections 19.2, 19.3.4, 19.4.1), undergo acyl addition (Chapter 18, Sections 18.1-18.7), and participate in enolate anion reactions (Chapter 22, Sections 22.2, 22.4, 22.6). Based on these reactions, several disconnections are shown, but several more are possible. 

Discoimection of other combinations of functional groups can lead us back to a 1,6-dicarbonyl compound. Try this on TM 201. 

The reactivity of alkylthiazoles possessing a functional group linked to the side-chain is discussed here neither in detail nor exhaustively since it is analogous to that of classical aliphatic and aromatic compounds. These reactions are essentially of a synthetic nature. In fact, the cyclization methods discussed in Chapter II lead to thiazoles possessing functional groups on the alkyl chain if the aliphatic compounds to be cyclized, carrying the substituent on what will become the alkyl side chain, are available. If this is not the case, another functional substituent can be introduced on the side-chain by cyclization and can then be converted to the desired substituent by a classical reaction. 

The presence of other functional groups ia an acetylenic molecule frequendy does not affect partial hydrogenation because many groups such as olefins are less strongly adsorbed on the catalytic site. Supported palladium catalysts deactivated with lead (such as the Liadlar catalyst), sulfur, or quinoline have been used for hydrogenation of acetylenic compound to (predominantiy) cis-olefins. 

This tendency is especially significant in compounds containing functional groups capable of addition with the formation of both five- and six-membered rings. It has been shown that for amides and hydrazides of azolecarboxylic acids, selectively, and for the acids with any arrangement of a function and triple bond, heterocyclization always leads to the closure of the six-membered ring. Similar reactions in the benzoic series mainly lead to the formation of five-membered rings. 

A sequence of straightforward functional group interconversions leads from 17 back to compound 20 via 18 and 19. In the synthetic direction, a base-induced intramolecular Michael addition reaction could create a new six-membered ring and two stereogenic centers. The transformation of intermediate 20 to 19 would likely be stereoselective substrate structural features inherent in 20 should control the stereochemical course of the intramolecular Michael addition reaction. Retrosynthetic disassembly of 20 by cleavage of the indicated bond provides precursors 21 and 22. In the forward sense, acylation of the nitrogen atom in 22 with the acid chloride 21 could afford amide 20. 

Removal of the carbonate ring from 7 (Scheme 1) and further functional group manipulations lead to allylic alcohol 8 which can be dissected, as shown, via a retro-Shapiro reaction to give vinyl-lithium 9 and aldehyde 10 as precursors. Vinyllithium 9 can be derived from sulfonyl hydrazone 11, which in turn can be traced back to unsaturated compounds 13 and 14 via a retro-Diels-Alder reaction. In keeping with the Diels-Alder theme, the cyclohexene aldehyde 10 can be traced to compounds 16 and 17 via sequential retrosynthetic manipulations which defined compounds 12 and 15 as possible key intermediates. In both Diels-Alder reactions, the regiochemical outcome is important, and special considerations had to be taken into account for the desired outcome to. prevail. These and other regio- and stereochemical issues will be discussed in more detail in the following section. 

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