Secondary cyclic

Conflicting findings have been reported with thiols and in one case a hemiacetal was dehydrated to a dihydrofuran. A by-product found in varying amounts in the oxidation of secondary, cyclic alcohols is the corresponding thiomethoxymethyl ether. 

That an aminal is a necessary intermediate was first questioned by Herr and Heyl (2). They found that by using a slight excess of amine the yield of the enamine from two of the steroidal aldehydes studied was 84%. Also, the -fluorocnamines discussed earlier are formed in 60-90% yield from equimolar amounts of the 8-fluoroaldehyde and secondary cyclic amine (27). However, neither of these studies was specifically designed to show whether or not aminals were intermediates. 

Russian workers have studied secondary cyclic phosphites (113) and (114). Unfortunately, the situation is far from clear since m-(115) iso-nierizes to trans- 16) on standing, " but (117) is suggested to be thermodynamically more stable than (118). This apparent contradiction could be explained by either an incorrect assignment of isomers or a 1,3-interaction of the 4-methyl group in (114). 

HNR2R3 = secondary cyclic, acyclic and primary amines... 

Allyl Alcohols. Secondary cyclic allylic alcohols are reduced with the combination of Et3SiH and ethereal LiC104, even in the presence of a tertiary alcohol (Eq. 35) or ketal function.173 Primary allylic alcohols do not undergo deoxygenation under similar conditions.173... 

Enantiomerically pure compounds of type 208 have been synthesized and submitted to asymmetric Michael addition with secondary cyclic amines such as A -methylpiperazine to give enantiomerically pure derivatives 209 (Equation 20) <2004AF35>. 

The demethylated secondary cyclic base is also produced as a byproduct. 

The constants of ion pair formation of 33 amines with 2,4-dinitrophenol in benzene (Ab) have been compared with the pAa in water56. The effects of structural variations on basicity are larger in water than in benzene for primary and secondary cyclic amines, but similar for tertiary amines. The Taft and Hancock equation [where <7 has the usual meaning and E° (R ) is the steric effect of a component substituent]... 

Other papers of interest in this section report transamination of camphor-3-carbothioamides with secondary cyclic amines, reaction of camphorquinone with dimethyl /S-ketoglutarate, the use of fenchone (212 X=0) in alkene formation from Grignard reagents, bromination of 2-e/itfo-6-endo-dibromobornane to yield 2,3,6-endo-tribromoborn-2-ene, and camphor-enol trimethylsilyl ether formation by quenching the reaction mixture of butyl-lithium and camphor tosyl-hydrazone with trimethylsilyl chloride. ... 

The chemo- and regiospecific palladium-catalyzed four-component reaction of aryl iodides followed by incorporation of carbon monoxide, a polymer-supported allene, and a range of secondary cyclic amines has been reported as a short and high-yielding route to complex heterocycles with three points of diversity, such as 7 <2000CC2241>. 

The results show that a number of ruthenium carbonyl complexes are effective for the catalytic carbonylation of secondary cyclic amines at mild conditions. Exclusive formation of N-formylamines occurs, and no isocyanates or coupling products such as ureas or oxamides have been detected. Noncyclic secondary and primary amines and pyridine (a tertiary amine) are not effectively carbonylated. There appears to be a general increase in the reactivity of the amines with increasing basicity (20) pyrrolidine (pKa at 25°C = 11.27 > piperidine (11.12) > hexa-methyleneimine (11.07) > morpholine (8.39). Brackman (13) has stressed the importance of high basicity and the stereochemistry of the amines showing high reactivity in copper-catalyzed systems. The latter factor manifests itself in the reluctance of the amines to occupy more than two coordination sites on the cupric ion. In some of the hydridocar-bonyl systems, low activity must also result in part from the low catalyst solubility (Table I). 

The reaction of 2,4-dinitrophenyl benzoate with secondary cyclic amines in DMSO-water shows a break in a Bronstcd plot near pKa 9.1 and the microconstants for the various stages in the reaction have been obtained and these gave good straight line Bronstcd plots.46 The a-effect was observed as a positive deviation in the linear log k vs pXa plot for the reaction of /7-nitrophcnyl X-substituted benzoates (43) with primary... 

Scheme 3.9 Secondary cyclic and bicyclic tertiary fluorides...

More importantly, this silver system catalyzes the intermolecular amination of hydrocarbons, as shown in Table 6.3. In addition to animating weaker benzylic C-H bonds, stronger aliphatic C-H bonds such as those in cyclohexane were also reactive. Although yields with more inert hydrocarbons were modest with the bathophenan-throline system, the discovery of the first silver-catalyzed intermolecular amination opens opportunities for further developments. This reaction favored tertiary cyclic sp3 C-H bonds over secondary cyclic sp3 C-H bonds, and showed limited success with simple linear alkanes. No conversion was observed with any aromatic C-H bonds. The compound NsNH2 was tested as the nitrene precursor with different oxidants. The use of PhI(OAc)2 as oxidant gave the expected amination product with a lower yield, while persulfate and peroxides showed no reactivity. 

Simple 1,1-enediamines react with diethyl azodicarboylate (182, R = Et) to give mainly, after hydrolysis, A/,7V -dicarboethoxyhydrazinylamides (183) in low to moderate yields (equation 74). A small amount (6%) of [2 + 4] cycloaddition product was also isolated in the case of 1,1-dipiperidinylethylene 35 (X = CH2)146. Secondary cyclic 1,1-enediamines 8, 75a and 77 react with diethyl azodicarboxyiate smoothly at room temperature to afford excellent yield of C-adducts 18429,39. 1,1-Enediamines 185 also led to adduct 17 or 17 when refluxed with 182 in methylene chloride (Scheme 10)37 147 see section h a for tautomerization between 17, and 17 ). An ene-addition... 

The mesoionic 2-T-cycloalkylamino-5-alkyl-l,3-dithiolium-4-thiolates 504 were prepared from 1,3-dithiocarbamoyl acid 503 in a retro-1,3-dipolar cycloaddition reaction. The acids were obtained by S-alkylation of triethylammonium 1,3-dithiocarbamates 501, easily synthesized from secondary cyclic amines 500 and CS2, with bromo acids 502 (Scheme 72) <1996PS75, 2002HC0593>. 

Spiro compound 45 reacts with secondary cyclic amines to produce 536a (equation 188). On the other hand the spiro compound 45 in reaction with aniline gives a lactam (537) via sequential 1,5-addition and internal acylation. Even the weakly nucleophilic pyridine reacts with 45 to give the betaine 538 (equation 188) . 

Boyer and co-workers studied the sulphuric acid-catalysed decomposition of three secondary cyclic azides cyclopentyl, cyclohexyl and cycloheptyl, and found that ring expansion, i.e. alkyl migration, competes quite favourably with hydrogen migration. For example, cyclopentyl azide in chloroform, gave cyclopentanone (as its 2,4-dinitrophenylhydrazone, 2-2%) and piperideine (5) (79 8%), on... 

Morpholine is a secondary, cyclic amine which reacts with aldehydes and ketones to give enamines with the formation of water. 

Quach and Batey299 reported the coupling of primary amines with phenylboronic acids catalyzed by Cu(OAc)2 (10 mol%) without base or ligand but in the presence of 4 A molecular sieves and air in CH2C12 solvent (equation 73). Reactions of potassium phenyl-trifluoroborate also occurred, but in lower yields than reactions of boronic acids. They showed that these reactions occur with a variety of functional groups on the amine, including alkenes, esters, ketones and ketals. a-Amino acid derivatives underwent reaction without detectable epimerization. Anilines were poorer cross-coupling partners under these conditions than were primary and secondary cyclic aliphatic amines. 

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