Addition of aldehydes

Allylic carbonates are most reactive. Their carbonylation proceeds under mild conditions, namely at 50 C under 1-20 atm of CO. Facile exchange of CO2 with CO takes place[239]. The carbonylation of 2,7-octadienyl methyl carbonate (379) in MeOH affords the 3,8-nonadienoate 380 as expected, but carbonylation in AcOH produces the cyclized acid 381 and the bicyclic ketones 382 and 383 by the insertion of the internal alkene into Tr-allylpalladium before CO insertion[240] (see Section 2.11). The alkylidenesuccinate 385 is prepared in good yields by the carbonylation of the allylic carbonate 384 obtained by DABCO-mediated addition of aldehydes to acrylate. The E Z ratios are different depending on the substrates[241]. 

The Paal synthesis of thiophenes from 1,4-diketones, 4-ketoaldehydes and 1,4-dialdehydes has found great use in the synthesis of medicinally active compounds, polymers, liquid crystals and other important materials. Furthermore, the discovery of the catalyzed nucleophilic 1,4-conjugate addition of aldehydes, known as the Stetter reaction (Eq. 5.4.1), has enabled widespread use of the Paal thiophene synthesis, by providing 1,4-diketones from readily available starting materials. ... 

The modified NBR samples were characterized by differential scanning calorimetry [11,78-80,98]. The glass-transition temperature (T ) decreased with the level of hydrogenation. In the case of HFNBR, Tg increased with an increase in the addition of aldehyde groups to the polymer chain. Thermogravimetric analysis of the modified polymers have also been carried out [15]. 

The condensation of 2,5-diunsubstituted pyrroles with formic acid20 is a viable method to produce porphyrins. However, the most common procedure21 22 involves the heating of the corresponding pyrroles 1 with aldehydes and aldehyde derivatives like imines or a Mannich reagent in the presence of acid. The reaction is initiated by electrophilic attack of the aldehyde (or aldehyde derivative) to the pyrrole 1. The formed (hydroxyalkyl)pyrrole 3 then undergoes electrophilic substitution with another pyrrole to form a dipyrrylmethane 4. Repeated addition of aldehyde and pyrrole finally forms a tetrameric (hydroxyalkyl)bilane 5. 

High -/-selectivity in the addition of aldehydes and ketones is also reported for [1,1,2-tris-(phenyllhio)-2-propenyl]lithium91 and [l,l-bis(isopropylthio)-2-methyl-2-propenyl]lithium92. No selectivity is observed with ( )-2-lithio-2-(2-phcnvlcthcnyl)-l,3-dithianc93, but essentially complete a-selectivity occurs in the presence of boron trifluoride-diethyl ether. 

In a similar way. ft-keto imide 19 undergoes stereodivergenl aldol reactions. Thus, conversion of 19 into the tin enolate, and subsequent addition of aldehydes, give predominantly the diastereomers 20. On the other hand, hydroxy ketones 21 are the main products when the chlorotitanium enolate of 19 is reacted with aldehydes53. ... 

Table 3. /J-Sulfinyl Alcohols by Addition of Aldehydes to Metalated (/m-Butylsulfinylmethyl)benzene...

Table 4. Sulfinylalkcnols by Addition of Aldehydes to Vinyl Sulfoxides1J...

Table 6. 5-Oxoalkanoates by Addition of Aldehyde or Ketone SAMP I tydra/ones to F.nones...

Aldehydes, formates, primary, and secondary alcohols, amines, ethers, alkyl halides, compounds of the type Z—CH2—Z, and a few other compounds add to double bonds in the presence of free-radical initiators/ This is formally the addition of RH to a double bond, but the R is not just any carbon but one connected to an oxygen or a nitrogen, a halogen, or to two Z groups (defined as on p. 548). The addition of aldehydes is illustrated above. Formates and formamides " add similarly ... 

Polymers are often side products. Photochemical addition of aldehyde to conjugated C=C units can be efficient when a triplet sensitizer (p. 316) such as benzophenone is... 

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. ... 

Addition of alcohols or phenols to alkynes addition of aldehydes or... 

Free-radical addition of aldehydes or ketones to alkenes... 

Coumalic acid, 56, 51 Crotyl fluoride, 57,73 18-CROWN-6,57, 30 Curtius rearrangement, 59, 1 Cyanide ion, as catalyst for conjugate addition of aldehydes, 59, 56 p-Cyanobenzenesulfonyl cyanide, 57, 89 2-( 1 -Cyanocyclohexyljhydrazinecarboxylic acid methyl ester, 58,102 Cy a noferrocene, 56, 30 Cyanogen chloride, 57, 88... 

Keto nitriles, by cnnjugate addition of aldehydes, 59,5 6 KETONES, acetylemic, 55, 52... 

Thioazolium ions, as catalysts for conjugate addition of aldehydes, 59, 57 Thiobutyric acid, 55, 129, 131 Thioketals, conversion to vinyl sulfides,... 

The addition of aldehydes to N3P3CI6 in the presence of pyridine has also been studied. 

Krische et al. demonstrated intramolecular reaction with Co(dpm)2 (5mol%) and PhSiH3 (120 mol %) as a hydride donor (Scheme 8) [14-16]. Addition of aldehyde-enone 17 to a solution of the Co catalyst and phenylsi-lane resulted in the formation of the corresponding aldol cyclization product... 

In a variation of the usual reaction conditions for oxidising furfuraldehyde to 2-furoic acid with hypochlorite, the aldehyde was added dropwise to a 10% excess of commercial sodium hypochlorite solution at 20-25°C, but without the inclusion of additional sodium hydroxide. When aldehyde addition was almost complete, a violent explosion occurred. Subsequent investigation showed that the pH of the reaction mixture fell progressively with addition of aldehyde, and at pH 8.5 the reaction mixture erupted violently, the temperature increased by 70°C and the pH fell to 2. Similar results were seen with benzaldehyde, but not with thiophene-2-aldehyde. 

Betaines may be considered to be the intermediate products in the displacement of the C—O fragment from the P—C—O—B system, whereas the addition of aldehydes to the P—C—O—B system constitutes the first stage. This reaction is due to the fact that phosphorus and boron atoms can change their coordination reversibly and convert into the tetra-coordinated state. The displacement of one aldehyde by another is carried out in a solvent or in excess aldehyde. In general this reaction is represented by the following scheme [Eq. (107)]. 

The familiar standard de carbonyl at ion mechanism ( 3, 5) involving a concerted oxidative-addition of aldehyde, CO migration (with subsequent elimination), and reductive-elimination of product, would seem with metalloporphyrins to require coordination numbers higher than six, and in this case Ru(IV) intermediates. Although this is plausible, the data overall strongly suggest a radical mechanism and Ru(III) intermediates. 

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