Heterocycles from alcohols

N- ondensed heterocyclics from alcohols by intramolecular N-alkylation... 

Yin W, Wang C, Huang Y (2013) Highly practical synthesis of nitriles and heterocycles from alcohols under mild conditions by aerobic double dehydrogenative catalysis. Org Lett 15(8) 1850-1853... 

Chiral heterocyclic compounds containing vicinal oxygen and nitrogen atoms were achieved by an asymmetric Diels-Alder reaction [111] of chiral acylnitroso dienophiles 111. The latter were prepared in situ from alcohols 110, both antipodes of which are available from camphor, and trapped with dienes (Scheme 2.46). Both the yield (65-94 %i) and diastereoisomeric excess (91-96%) were high. 

The 2-aminophenethyl alcohols resulting from condensation of ort/io-nitrotoluenes are good precursors for preparation of indoles. Watanabe and coworkers have developed ruthenium-catalyzed dehydrogenative iV-heterocyclization for synthesis of indoles and other heterocycles from 2-aminophenethyl alcohols or 2-nitrophenylethyl alcohols (Eq. 10.52). 69a The oxidative cycli-zation of 2-aminophenethyl alcohols are also catalyzed by Pd-based catalysts.69... 

A very few examples of the use of aryl-tin,21 -lead,21 -lithium43 and -magnesium21143,44 derivatives as the source of the aryl group in vinyl substitutions have been reported. Tin derivatives have been used with palladium dichloride bis(benzonitrile) and a copper(II) chloride reoxidant in a regioselective synthesis of oxygen heterocycles from unsaturated alcohols.43... 

Knowledge of these rules was used to isolate individual tautomers of compound 429 [431] (Scheme 3.140). This heterocycle is crystallized from alcohols and chloroform in the imine tautomeric form B, while in trifluoroacetic acid solution the dimethylamino group undergoes a protonation leading to... 

Substltuted thiophenes (not readily available, since both electrophilic substitution and metallatlon take place at position 2) can be prepared from the readily avallablg 3-bromothlophene by Pd(0Ac)2-catalyzed reaction with allyllc alcohols. This process has be n extended to the preparation of 3-alkyIpyridines from 3-bromopyrldine, as well as a variety of vinyl-substituted heterocycles from the corresponding bromo precursors. 

T. Iwahama, S. Sakaguchi, Y. Ishii, Epoxidation of alkenes with H2O2 generated in situ from alcohols and molecular oxygen using N-hydroxyphthalimide and hexafluoroacetone as catalysts. Heterocycles. 52 (2000) 693. 

Salts of o-halogeno-N-heterocyclics, such as 2-fluoro-l-methylpyri-dinium tosylate, and related compounds have been used successfully in a variety of reactions, particularly as agents for esterification, lactoni-zation, and the preparation of amides and thiolic esters They have been used also for the preparation of iodides from alcohols and acid fluorides from the acids as well as for Beckmann rearrangements and reductions, e.g. of a-hydroxyketones to ketones . Various condensed heterocyclic salts have been prepared from l-acylmethyl-2-chloropyridinium salts 2-Dialkylaminopyridinium salts have been used as phase transfer catalysts... 

The telomerization of dienes with alcohols as the nucleophile has now been conducted in a practical fashion. A palladium catalyst containing an N-heterocyclic carbene ligand has been shown to form linear dimeric ethers selectively from alcohols and butadiene with remarkably high turnover numbers (Equation 22.40). The activity of this catalyst is significantly higher than that of the more classical catalysts generated from Pd(OAc)j and PPhj. Under optimized conditions involving some added carbene precursor, presumably to... 

Miscellaneous Reactions. In certain cases, unexpected reactions occur with LR. The formation of the thiophosphate (119) from the corresponding phosphite has already been mentioned. Similarly, dimethyl thiophosphite can be obtained from dimethyl phosphite. Heterocyclic halobenzyl alcohols are deoxygenated by LR under microwave irradiation in the presence of molybdenum hexacarbonyl as catalyst without concomitant dehalogenation. Thiirene-1-oxides with bulky substituents (163, R = ferf-butyl, 1-adamantyl) are reduced and thionated under... 

SodiumI alcohol 2-Alkoxy-l,3-N,N-heterocyclics from N-heterocyclic oxime tosylates... 

Lead tetraacetate pyridine 1,1-Diacoxy compds. from alcohols with N-heterocyclic ring contraction... 

Oxazolidiones. A moderate phosgene-stream passed 0.5 hr. at room temp, into abs. benzene, then the temp, raised to 55-60°, a soln. of trimethylsilyl N-trimethyl-silyl-L-leucinate in the same solvent added dropwise with stirring, introduction of phosgene continued 1 hr., the above temp, maintained for 2-5 hrs., and allowed to stand at room temp, overnight L-leucine N-carboxyanhydride. Y 96%. F. e. and heterocyclics from N,0-disilylated amino-alcohols and -phenols, s. H. R. Kricheldorf, B. 103, 3353 (1970) f. methods and reactivity of silyloxy groups cf. B. 104, 87 (1971). 

Potassium hydroxide/alcohol Heterocyclics from a-amino-), y-ethylenenitriles Benzimidazoles and benzoxazoles... 

Potassium/alcohol-irradiation N-Heterocyclics from azides with ring expansion... 

Dam JH, Osztrovszky G, Nordstrpm LU, Madsen R (2010) Amide synthesis from alcohols and amines catalyzed by ruthenium V-heterocyclic carbene complexes. Chem Eur J 16 6820... 

Zhang Y, Chen C, Ghosh SC, Li Y, Hong SH (2010) Well-defined V-heterocyclic carbene based ruthenium catalysts for direct amide synthesis from alcohols and amines. Organome-... 

Chen C, Zhang Y, Hongs H (2011) V-heterocyclic carbene based ruthenium-catalyzed direct amide synthesis from alcohols and secondary amines involvement of esters. J Org Chem... 

Pyridine phosphorus oxide chloride Ring contraction of l,3-S,S-heterocyclics with formation of chlorides from alcohols Alcohols from chlorides... 

---