Functionalized halides

Since the trapping of the lactam enolate with electrophiles should not be limited to nitroolefins, extension to conjugate additions to alkenylsulfones, the ring opening of N-tosylaziridines, alkylation with functionalized halides, and silylation with chlorotrimethylsilane were explored. 

Much less has been done with the functionalized halides than with the functionalized olefins. The only two-carbon compound in this group is vinyl bromide (or iodide). This is a very useful reactant with secondary amines because terminal allylic amines are usually major or exclusive products. We have used this halide for synthesizing the pheromone of the Red Bollworm Moth, 9,11-docecadien-l-ol as follows (9). Of the four three-carbon functionalized vinylic halides listed,... 

The general synthetic route to six-coordinate (O—Sn) bis-chelates involves the reaction of a functionalized halide with metallic tin. In earlier papers the numerous examples of synthesis of estertinsX2Sn[CHRCHR COOR ]2 (X = Br, I R, R = H, Me, CH2COOR R" =, the amide derivatives X2Sn[CHRCHR CONR"R "]2 (X = Br, I R,... 

The advantages of using organozinc reagents for cross-coupling reactions are efficient transmetalation to palladium and ready availability, even directly from functionalized halides... 

Reactions between dialkyl hydrogenphosphonates and haloalkanes have been performed under phase-transfer conditions some initial experiments used diethyl and diisopropyl hydrogenphosphonates with either non-functionalized (e.g. alkyl, allyl or benzyl) halides, or functionalized halides, and employed K2CO3 as base in the presence of tetra-butylammonium salts or 18-crown-6. Other workers have also reported successes in their use of the same or similar systems, but more recent work has raised doubts about the value of the potassium salt, and has illustrated the evident superiority of CS2CO3 as base ... 

The 5-fluoro analog 531 was prepared by alkylation of 5-fluoro-l-hydro-xyuracil, via initial formation of its dianion with the appropriately functionalized halide 530 and then conventional deprotection [90JCS(P1)2175]. No significant activity was noted against herpes simplex virus type 1 and 2, varicella zoster, cytomegalovirus, or Epstein-Barr virus. 

Electrochemical reduction of organometallic assemblies, RmQ, where R is a o or 7r-complexed organic moiety, Q is oxy-function, halide or R, and m is a metal, indicate nine possible fates for the assembly... 

Highly functionalized halides give generally positive results. p-Iodo N-acetyl-alanine methyl ester was used to introduce the amino acid residue into an olefinic protected sugar (Fig. 57),300... 

A large variety of alkylation of functional halides with C-C bond formations of this type are now possible, many of them being catalyzed by Cu, Ni, Co, Fe and especially Pd complexes. 

Sml2 allows the use of functionalized halides where there is one site which selectively reacts (Girard et al., 1980) ... 

Salaita G N, Lu F, Laguren-Davidson L and Flubbard A T 1987 Structure and composition of the Ag(111) surface as a function of electrode potential in aqueous halide solutions J. Electroanal. Chem. 229 1-17... 

The process whereby aldehydes are produced from arylmethyl (also alkyl and other) halides by the action of hexamine is known as the Sommelet reaction. The reaction is essentially the conversion of an amine into an aldehyde the hexamine serves the dual role of converting the halide into the amine and the amine into the aldehyde, but its function is different in the two steps. When starting from a halide, the reaction proceeds in three stages —... 

CHEOPS is based on the method of atomic constants, which uses atom contributions and an anharmonic oscillator model. Unlike other similar programs, this allows the prediction of polymer network and copolymer properties. A list of 39 properties could be computed. These include permeability, solubility, thermodynamic, microscopic, physical and optical properties. It also predicts the temperature dependence of some of the properties. The program supports common organic functionality as well as halides. As, B, P, Pb, S, Si, and Sn. Files can be saved with individual structures or a database of structures. 

A saturated alkyl group does not exhibit functionality. It is not a d -synthon, because the functional groups, e.g. halide or metal ions, are lost in the course of the reaction. It functions as an alkyl synthon. Alkenyl anions (R. West, 1961) on the other hand, constitute d -synthons, because the C = C group remains in the product and may be subject to further synthetic operations. 

Palladium-catalyzed coupling reactions of organic halides with olefins or dienes (R. F. Heck, 1979) are broad in scope and simple to carry out. Anhydrous conditions or any special technique are not required and most functional groups are tolerated. 

Organic compounds are grouped into families according to the functional groups they contain Two of the most important families are alcohols and alkyl halides Alco hols and alkyl halides are especially useful because they are versatile starting materials for preparing numerous other families Indeed alcohols or alkyl halides—often both— will appear m virtually all of the remaining chapters of this text... 

It IS convenient m equations such as this to represent generic alcohols and alkyl halides as ROH and RX respectively where R stands for an alkyl group In addition to con venience this notation lets us focus more clearly on the functional group transformation that occurs the OH functional group of an alcohol is replaced as a substituent on car bon by a halogen usually chlorine (X = Cl) or bromine (X = Br)... 

While developing the connections between structure reaction and mechanism we will also extend the fundamentals of lUPAC nomenclature to functional group families beginning with alcohols and alkyl halides... 

The lUPAC rules permit alkyl halides to be named m two different ways called func twnal class nomenclature and substitutive nomenclature In functional class nomencla ture the alkyl group and the halide (fluoride chloride bromide or iodide) are desig nated as separate words The alkyl group is named on the basis of its longest continuous chain beginning at the carbon to which the halogen is attached... 

Alcohols and alkyl halides are classified as primary secondary or tertiary according to the degree of substitution of the carbon that bears the functional group (Section 2 13) Thus primary alcohols and primary alkyl halides are compounds of the type RCH2G (where G is the functional group) secondary alcohols and secondary alkyl halides are compounds of the type R2CHG and tertiary alcohols and tertiary alkyl halides are com pounds of the type R3CG... 

Many of the properties of alcohols and alkyl halides are affected by whether then-functional groups are attached to primary secondary or tertiary carbons We will see a number of cases m which a functional group attached to a primary carbon is more reac live than one attached to a secondary or tertiary carbon as well as other cases m which the reverse is true... 

The carbon that bears the functional group is sp hybridized m alcohols and alkyl halides Figure 4 1 illustrates bonding m methanol The bond angles at carbon are approximately tetrahedral as is the C—O—H angle A similar orbital hybridization model applies to alkyl halides with the halogen connected to sp hybridized carbon by a ct bond Carbon-halogen bond distances m alkyl halides increase m the order C—F (140 pm) < C—Cl (179 pm) < C—Br (197 pm) < C—I (216 pm)... 

Table 4 2 lists the boiling points of some representative alkyl halides and alcohols When comparing the boiling points of related compounds as a function of the alkyl group we find that the boiling point increases with the number of carbon atoms as it does with alkanes... 

Alkyl halides are such useful starting materials for preparing other functional group types that chemists have developed several different methods for converting alcohols to alkyl halides Two methods based on the inorganic reagents thionyl chloride and phosphorus tnbromide bear special mention... 

Thionyl chloride and phosphorus tribromide are specialized reagents used to bring about particular functional group transformations For this reason we won t present the mechanisms by which they convert alcohols to alkyl halides but instead will limit our selves to those mechanisms that have broad applicability and enhance our knowledge of fundamental principles In those instances you will find that a mechanistic understand mg IS of great help m organizing the reaction types of organic chemistry... 

Chemical reactivity and functional group transformations involving the preparation of alkyl halides from alcohols and from alkanes are the mam themes of this chapter Although the conversions of an alcohol or an alkane to an alkyl halide are both classi tied as substitutions they proceed by very different mechanisms... 

This concludes discussion of our second functional group transformation mvolv mg alcohols the first was the conversion of alcohols to alkyl halides (Chapter 4) and the second the conversion of alcohols to alkenes In the remaining sections of the chap ter the conversion of alkyl halides to alkenes by dehydrohalogenation is described... 

Table 8 1 illustrates an application of each of these to a functional group transfer matron The anionic portion of the salt substitutes for the halogen of an alkyl halide The metal cation portion becomes a lithium sodium or potassium halide... 

Representative Functional Group Transformations by Nucleophilic Substitution Reactions of Alkyl Halides... 

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