Addition reactions Aldehydes Alkenes Alkynes

Methylarsine, trifluoromethylarsine, and bis(trifluoromethyl)arsine [371-74-4] C2HAsF, are gases at room temperature all other primary and secondary arsines are liquids or solids. These compounds are extremely sensitive to oxygen, and ia some cases are spontaneously inflammable ia air (45). They readily undergo addition reactions with alkenes (51), alkynes (52), aldehydes (qv) (53), ketones (qv) (54), isocyanates (55), and a2o compounds (56). They also react with diborane (43) and a variety of other Lewis acids. Alkyl haUdes react with primary and secondary arsiaes to yield quaternary arsenic compounds (57). 

In organic chemistry, reduction is defined as a reaction in which a carbon atom forms fewer bonds to oxygen, O, or more bonds to hydrogen, H. Often, a C=0 bond or C=C bond is reduced to a single bond by reduction. A reduction that transforms double C=C or C=0 bonds to single bonds may also be classified as an addition reaction. Aldehydes, ketones, and carboxylic acids can be reduced to become alcohols. Alkenes and alkynes can be reduced by the addition of H2 to become alkanes. 

The chemistry of alkynes is dominated by electrophilic addition reactions, similar to those of alkenes. Alkynes react with HBr and HC1 to yield vinylic halides and with Br2 and Cl2 to yield 1,2-dihalides (vicinal dihalides). Alkynes can be hydrated by reaction with aqueous sulfuric acid in the presence of mercury(ll) catalyst. The reaction leads to an intermediate enol that immediately isomerizes to yield a ketone tautomer. Since the addition reaction occurs with Markovnikov regiochemistry, a methyl ketone is produced from a terminal alkyne. Alternatively, hydroboration/oxidation of a terminal alkyne yields an aldehyde. 

Triple bonds can be monohydroborated to give vinylic boranes, which can be reduced with carboxylic acids to cis alkenes or oxidized and hydrolyzed to aldehydes or ketones. Terminal alkynes give aldehydes by this method, in contrast to the mercuric or acid-catalyzed addition of water discussed at 15-4. However, terminal alkynes give vinylic boranes (and hence aldehydes) only when treated with a hindered borane such as 47, 48, or catecholborane (p. 798)," or with BHBr2—SMe2. The reaction between terminal alkynes and BH3 produces 1,1-... 

Similar reactions have been carried out on acetylene. Aldehydes add to alkynes in the presence of a rhodium catalyst to give conjugated ketones. In a cyclic version of the addition of aldehydes, 4-pentenal was converted to cyclopen-tanone with a rhodium-complex catalyst. In the presence of a palladium catalyst, a tosylamide group added to an alkene unit to generate A-tosylpyrrolidine derivatives. ... 

Enynes 71 react with aldehydes 61 in the presence of the [Ni(COD)J/SIPr catalytic system to afford two distinct products 72 and 73 (Scheme 5.20) [20b], The enone 72 is derived from aldehyde addition with the alkyne moiety while the adduct 73 arises from the aldehyde addition with the alkene moiety. The product distribution is dependent on the substituent on either the alkyne or alkene moieties. The reaction between 71 and ketones 74 led to the unprecedented formation of pyrans 75 (Scheme 5.20). The reaction showed to be highly regioselective in aU the cases, the carbonyl carbon was bound to the olefin. 

Because organophosphorus compounds are important in the chemical industry and in biology, many methods have been developed for their synthesis [1]. This chapter reviews the formation of phosphorus-carbon (P-C) bonds by the metal-catalyzed addition of phosphorus-hydrogen (P-H) bonds to unsaturated substrates, such as alkenes, alkynes, aldehydes, and imines. Section 5.2 covers reactions of P(lll) substrates (hydrophosphination), and Section 5.3 describes P(V) chemistry (hydrophosphorylation, hydrophosphinylation, hydrophosphonylation). Scheme 5-1 shows some examples of these catalytic reactions. 

Nitrogen-containing heterocyclic compounds, including 1,2,3,4-tetrahydroqui-noline, piperidine, pyrrolidine and indoline, are also popular hydrogen donors for the reduction of aldehydes, alkenes, and alkynes [75, 76]. With piperidine as hydrogen donor, the highly reactive 1-piperidene intermediate undergoes trimer-ization or, in the presence of amines, an addition reaction [77]. Pyridine was not observed as a reaction product. 

The meso-ionic 1,3-oxazol-S-ones show an incredible array of cycloaddition reactions. Reference has already been made to the cycloaddition reactions of the derivative 50, which are interpreted as involving cycloaddition to the valence tautomer 51. In addition, an extremely comprehensive study of the 1,3-dipolar cycloaddition reactions of meso-ionic l,3-oxazol-5-ones (66) has been undertaken by Huisgen and his co-workers. The 1,3-dipolarophiles that have been examined include alkenes, alkynes, aldehydes, a-keto esters, a-diketones, thiobenzophenone, thiono esters, carbon oxysulfide, carbon disulfide, nitriles, nitro-, nitroso-, and azo-compounds, and cyclopropane and cyclobutene derivatives. In these reactions the l,3-oxazol-5-ones (66)... 

Addition reactions occur in compounds having n electrons in carbon-carbon double (alkenes) or triple bonds (alkynes) or carbon-oxygen double bonds (aldehydes and ketones). Addition reactions are of two types electrophilic addition to alkenes and alkynes, and nucleophilic addition to aldehydes and ketones. In an addition reaction, the product contains all of the elements of the two reacting species. 

In addition, the same authors showed that ,/ -unsaturated aldehydes 132 could act both as CO and alkene source and give the PK products 134 upon reaction with different alkynes (133) (Scheme 41). As part of their study, they performed a cross reaction of cinnamaldehyde and a substituted styrene with phenylacetylene, isolating two PK products coming from both alkenes. This is a proof for a decarbonylative-[2 + 2+1] reaction pathway [147]. 

Trialkylgermanes add to carbon-carbon triple bonds in the presence of transition metal catalyst [41]. A review on fhe addition-i-reaction of Ge-H functional organo-germane compounds R GeH4 to unsaturated compounds (alkenes, alkynes, ketones, aldehydes) has been published [42]. 

---