Tertiary alkenylation

Classify each of the following organic halides as primary, secondary, tertiary, alkenyl, or aryl. PRACTICE PROBLEM 6.2 Br... 

R may be methyl or primary secondary or tertiary alkyl it may also be a cycloalkyl alkenyl or aryl group)... 

Despite the great success of the transmetalation process in the enantiose-lective arylation of ketones, its extension to allylation or alkynylation reactions failed, providing the corresponding tertiary alcohols with enantiomeric excesses never higher than 50% ee. On the other hand, more success has been found in the alkenylation of ketones. The process started with the hydrozirconation of terminal alkynes to give the corresponding alkenylzirconium intermediates, which were transmetalated by reaction, in this case, with various ketones in the presence of the HOCSAC ligand. This protocol tolerated the presence of other carbon-carbon multiple bonds on the alkyne, as well as different functionalities and achieved excellent results for alkyl ketones, a,(3-unsaturated ketones and even dialkylketones, as shown in Scheme 4.22. 

The current procedure starts with the ester, ethyl 1-naphthoate, and converts it into homologated product in 81% yield without isolation of any intermediates. Safe, commercially available materials are employed. Based on a recently published variation43 of our original homologation methods,4 1 It represents a general procedure applicable to esters 1 bearing aryl, alkenyl, alkynyl and primary, secondary or tertiary alkyl attachments R. Yields range from 67-90% (on a 25-mmol scale) and like the Arndt-Eistert sequence this procedure affords retention of stereochemistry for the... 

The action of chloroamine and bromoamine on organometallic reagents has been reviewed102 and a comprehensive review of electrophilic aminations of carbanions has appeared103. Alkyl, alkenyl and aryllithium compounds are converted into tertiary amines 84 by reaction with the mesityl compounds 83 (R2 = Me or Et Ar = 2,4, 6-MesCeHj)104. 

In the preceding cyclization, one concern is the behavior of intermediate 24 if its benzyl cation is replaced with a tertiary cation to avoid forming a tertiary carbon, the 1,2-aryl migration of this intermediate would be unlikely to occur. When this cyclization was extended to 2,2-dimethyl(o-ethynyl)styrene 26, the 2-alkenyl-lH-indene product 28 [16] was obtained in 76% yield, as depicted in Scheme 6.14. In this transformation, the alkenyl double bond of the 3,5-dien-l-ynes is cleaved and a... 

Formation of aldehydes. Aldehydes can be prepared by the carbonylation of halides in the presence of various hydride sources. The carbonylation of aryl and alkenyl iodides and bromides with CO and H (1 1) in aprotic solvents in the presence of tertiary amines affords aldehydes[373,374]. Aryl chlorides, as tricarbonylchromium derivatives, are converted into aldehydes at 130 C[366], Sodium formate can be used as a hydride source to afford aldehydes. Chlorobenzene (514) was carbonylated at 150 °C to give benzaldehyde with CO and sodium formate by using dippp as a ligand[375,376]. 

By contrast, when the first electrophile was an aldehyde as illustrated for the reaction of 276 with benzaldehyde, the resulting alkenylmetal presumably became part of a six-membered ring alkoxide 279 and hence so poorly reactive that it did not even react with iodine. However, treatment with Me3SiCl resulted in the silylation of the secondary zinc alkoxide and allowed iodinolysis to subsequently proceed, affording the (Z)-alkenyl iodide 280 (equation 132)165. Unfortunately, this protocol was not efficient for tertiary alkoxides generated by initial reaction of 276 with ketones. 

Several procedures are known, including Rh catalysis, for the exo cyclization of alkenyl aldehydes such as 1 to ketones such as 2. Kiyoshi Tomioka of Kyoto University recently reported (J. Org. Chem. 2005, 70,681) that efficient cyclization can be achieved by merely heating the aldehyde with a catalytic amount of a tertiary thiol, with A1BN as the initiator. Addition takes place even to unactivated aikcnes, and both five- and six-membered ring ketones can be formed. It is a measure of the mildness of the method that cyclization of 1 gives 2 as a 1 1 mixture, even though trans is much the more stable diasteromer. 

Hydroperoxide formation is characteristic of alkenes possessing tertiary allylic hydrogen. Allylic rearrangement resulting in the formation of isomeric products is common. Secondary products (alcohols, carbonyl compounds, carboxylic acids) may arise from the decomposition of alkenyl hydroperoxide at higher temperature. 

Amines. Aliphatic mono-, di-, and polyamines derived from fatty and main acids make up this class of surfactants. Primary, secondary, and tertiary monoamines with Qg alkyl or alkenyl chains constitute the bulk of diis class. The products are sold as acetates, naphdienales, or oleates. Principal uses are as ore-flotation agents, corrosion inhibitors, dispersing agents, wetting agents for asphalt, and as intermediates for the production of more highly substituted derivatives... 

Secondary and tertiary dialkylcuprates, lithium dialkenyl-, and even diphenyl-cuprates, add in very good yields to the reactive propionaldehyde diethyl acetal. The syn addition products may be trapped with a variety of electrophiles such as alkyl, alkenyl, alkynyl and aryl halides. The method has been used for the synthesis of several natural products. Substituted alkynic acetals also react with lithium dialkylcuprates in ether to furnish stable dialkenylcuprates of type (128) which do not eliminate to the corresponding alkoxy allenes (129) if the temperature is maintained below -20 C.164-179... 

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