Substituted ketones, 511 crystalization

Benzene formed from photolysis of the 1 1 complex is a cage-escape product from 3(Jul-CHO+ /Ph ). Benzene formed from the photolysis of the 2 1 complex is an in-cage product from 3((Jul-CHO)2 /Ph ). The formation of 2 1 complexes of amino-substituted ketones and iodonium salts has been suggested to account for the high photosensitivity of polymeric Mannich bases with iodonium salts [102]. Formation of 2 1 donor iodonium cation complexes has been rationalized by consideration of the crystal structures of diphenyliodonium halides, which crystallize as dimers with square planar iodine atoms with two bridging halide counterions [102,108]. 

The reduction of a-phosphorus-substituted ketones of the general form 7 has also been quite thoroughly researched (Table 7 84i -84s. The product alcohols arc intermediates in Horner -Wittig type alkene syntheses, and can be induced to undergo stcreospecific syn elimination on conversion to the corresponding sodium or potassium (but not lithium) alkoxides. It is often possible to purify the alcohols by crystallization, allowing the synthesis of stereochemically homogeneous alkencs. 

Further exploitation of the molecular shape feature has led more recently to the design of another series of clathrate hosts by substituting on the allene rigid backbone bulky groups 22>, Representative compounds of this new host family are 20 and 21. The allene 20 (R = t-butyl) shows an interesting clathration behaviour upon crystallization from various environments, including alicyclic and aromatic compounds, heterocycles, cyclic ketones and eyclohexaneamine 26>. 

Based on a known synthesis of spiro compounds with six-membered rings [63] we succeeded in the stepwise assembly of terminal substituted mono-[64] and dispiranes [65]. Hereby the cyclisation of the dibromide 35 with TOSMIC (Iter. 1) is the keystep of the reaction sequence as the initial ketone functional group (36) is recovered. Four subsequent reactions led to the spirodibromide 40 (Iter. 2). Final spirocyclisation afforded the dispirane 41, representing a precursor for new calamitic liquid crystals (Fig. 16) [66]. 

The present method is successful with a wide variety of ketones (see Table). Cyclic ketones (entries 1-4, 8) produce benzoannelated products in excellent overall yields. There is no need to purify the intermediate both the nucleophilic addition of methallylmagnesium chloride and the aromatic cyclization take place cleanly. Acyclic ketones (entries 5-7) also provide high yields of benzoannelated product. Aromatic ketones are particularly interesting substrates for this reaction since they provide substituted biphenyls, which are potentially useful materials for liquid crystal synthesis and whose preparation through classical methodology is often not straightforward. The conditions for the cationic cyclization step can be modified to accommodate acid-sensitive functionality. For example, cyclization of 3 to 4, the latter a precursor for 3-methyl-8,14-dehydromorphinan, was accomplished in 77% yield by treatment of 3 at... 

Condensation of [3- or "y-amino alcohols with aldehydes or ketones RR CO gives the product 27. In solution the position of the equilibrium varies with R and R, and with the solvent (73). When the carbonyl reactant is a substituted benzaldehyde, the solid is found (IR, KBr) to comprise molecules of the open-chain structure 27a, whereas aliphatic aldehydes and ketones give crystals of dihydro- 1,3-benzoxazines, 27b. An interesting case is that of the condensation product of o-hydroxybenzylamine with cyclopentanone, for which McDonagh and Smith (73) suggest that ring and chain tautomers coexist in the solid. 

The solvent employed in the first commercial installation, of the Indian Refining Co., was a mixture of acetone and benzene (90% grade). In the subsequent development of the process by The Texas Co., a large number of solvents were found to be satisfactory. At present, the process normally employs a mixture of methyl ethyl ketone and industrial grade benzene, which have been found to be admirably suitable and provide a relatively low cost solvent. Toluene is substituted for all or part of the benzene when low chilling temperatures are required to obtain oils of very low pour point, as benzene may crystallize out from the mixture at these lower temperatures. 

In contrast to a-(phenyl-A3-iodanyl) ketones, it is possible to isolate a-(phenyl-A3-iodanyl) sulfone 60 as a stable crystal [100]. The sulfone 60 undergoes substitutions with various nucleophiles with reductive elimination of iodobenzene. 

Acylamino)benzaldehyde or 2 (acylamino)phenyl methyl ketone (0.01 mol) in sal. ethanolic NH, (10 mL) was kept al 20°C for 12 h and evaporated. The residue, dissolved in benzene, was passed through an alumina column and the eluaies were evaporated. The residue was crystallized from light petroleum (bp 60-80 C) if solid, or distilled if liquid, to give the required 2-alkyl-substituted quinazolines. 

Treatment of 2-aminomethylaziridine (59) with a variety of aromatic or aliphatic aldehydes or ketones in refluxing ethanol gives rise to several examples of 2-substituted l,3-diazabicyclo[3.1.0]hexanes 60. The NMR spectra of these diazabicyclohexanes have been reported and the crystal structure of 2-p-bromophenyl-l,3-diazabicyclo[3.1.0]hexane has been determined. ... 

Summary (Aminomethyl)silanes have been prepared by new synthetic routes starting from lithiosilanes or (lithiomethyl)amines. (Lithiomethyl)(aminomethyl)silanes were formed by metallation with lithioalkyls. A sulfur-substituted (lithiomethyl)(aminomethyl)silane and a THF adduct are characterized by single crystal X-ray diffraction. In reactions of (lithiomethyl)(aminomethyl)silanes with aldehydes or ketones no clear addition/depro-tonation profile was observed. 

Cp2Ti(CO)2 reacts with with 2 equiv. of cr,/ -unsaturated ketones to yield the nine-membered titana-2,9-dioxacy-clonona-3,7-dienes, which can be used for the selective synthesis of substituted cyclopentanols, diketones, or cyclopentenes. X-ray crystal structures and ab initio calculations have been reported.1544... 

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