Lithium aluminium hydride ring-opening with

Treatment of 19b with phenylmagnesium bromide gives diphenylacetylene (66) and the salt of benzenesulfmic acid Lithium aluminium hydride reacts with 19b similarly. These ring-opening reactions are similar to the reactions of organometallic reagents with the analogous thiirane dioxides (equation 17 above). 

In the synthesis of methyl corydalate (55) Nonaka et al. (65) used the methiodide of (-t-)-tetrahydrocorysamine (65) as substrate and the Hofmann degradation method for ring opening (Scheme 16). The methine base (66) on hydroboration afforded alcohol 67, identical with a product obtained from 55 by lithium aluminium hydride reduction. 

Allylpiperidines were formed from 3-iodomethylperhydropyrido[l,2-f][l,3]oxazin-l-ones by treatment with Zn in AcOH <2002OL3459>. l-Methyl-2-(2-hydroxyalkyl)piperidines were prepared from 3-substituted perhydropyr-ido[l,2-tf][l,3]oxazin-l-ones with lithium aluminium hydride (LAH) in boiling THF and EtzO <2005T1595>. Reaction of 8-methylperhydropyrido[ 1,2-r [ 1.3 ]oxazine-1,3-dione 103 with PhCH2NH2, then PhCOCl and 4-meth-oxyphenol afforded ring-opened products 104 and 105, respectively (Scheme 8) <2000JA11009>. 

Reduction of cycloalkane-condensed 2-phenyl-5,6-dihydro-4//-l,3-benzoxazines 144 with lithium aluminium hydride (LAH) afforded A -benzyl-substituted 2-(aminomethyl)cycloalkanols 145 in a reductive ring opening via the ring-chain tautomeric tetrahydro-l,3-oxazine intermediates. Catalytic reduction of 1,3-oxazines 144 under mild conditions in the presence of palladium-on-carbon catalyst similarly resulted in formation of the A -benzyl-1,3-amino alcohols 145. When the catalytic reduction was performed at elevated temperature at hydrogen pressure of 7.1 MPa, the N-unsubstituted 2-(aminomethyl)cycloalkanols 146 were formed in good yields (Scheme 22) <1998SC2303>. 

Although more rare, the ring opening of A-acyl (3-lactams has also been realized by using hydrides, giving rise to the corresponding reduction products. In this context, Scheme 40, Lee and Pak [107] have described the treatment of A-Boc (3-lactam 119 with lithium aluminium hydride to give A-protected amino alcohol 120. Compound 120 could serve as potential intermediate for the synthesis of various hydroxylated indolizidine alkaloids. 

The compound (70) by epoxide ring-opening with hydrogen fluoride, followed by photocatalysed addition of acetylene to the A16-bond and lithium aluminium hydride reduction, gave (71). Protection of the 1,2-diol system in (71) as the acetonide followed by oxidation, dehydration, and regeneration of the diol grouping produced... 

Bondavalli et al. have found some stereoselectivity in the reduction of the oxime (180) derived from 1,8-cineol. With lithium aluminium hydride it mostly gives the endo-amine (181), but with sodium in Jcohol the exo-amine predominates. The bromination of pinol (182) —not naturally occurring—has been shown by Wolinsky to occur with rearrangement. Wallach s structure is incorrect the product is 6,7-dibromo-1,8-cineol (183). Treatment of this with hydrogen bromide leads to the ring-opened pinol tribromide (184). de Mayo... 

Contrary to an earlier report,solanidine (33) and demissidine (34) have been found to react smoothly with cyanogen bromide with opening of ring e to give (47), a reaction which may be of synthetic utility.Lithium aluminium hydride... 

The product of the reaction with c/s-stilbene was a trichloroacetate ester which yielded the wcso-glycol upon reduction with lithium aluminium hydride the /raHs-olefin yielded the racemic glycol after the same treatment . Such reaction products are consistent with ring-opening of the epoxide by strong acid, and it was shown that (-)-rraHs-stilbene oxide reacted rapidly (relative to the rate of epoxidation) with trichloroacetic acid in benzene the overall observations are indicative of acid-catalysed epoxidation of stilbene but may admit other interpretations, one of which involves thermodynamic intervention of trichloroacetic acid dimer in a solvating capacity rather than in a truly kinetic function. 

Reaction of furyllithium (60) with L-threonine derived lithium salt 61 afforded the expected ketone 62 in 30% yield. Reduction of 62, using lithium aluminium hydride, gave two alcohols (63 and 64) in a 3 1 ratio. In both carbinols (63 and 64) the oxazoline ring was opened by acid hydrolysis to give the N-benzoyl derivatives 65 and 66, respectively. Alcohol 66 can be used in the synthesis of lincosamine enantiomer, but unfortunately this approach has limited preparative value because of the low yield obtained in the condensation step and, on the other hand, opposite diasteroselectivity obtained in the reduction reaction. 

Pyrazolidine Derivatives. The reduction of some aminopyrazole quaternary salts (301) with sodium borohydride or lithium aluminium hydride leads to pyrazolidinone derivatives, e.g. (302), and ring-opened products. ... 

Epoxy fatty acids (as the methyl esters) give El mass spectra which are not easily interpreted in terms of the position of the oxygen atom (especially when double bonds are also present), although it is possible with some effort if suitable model compounds are available [116,473,481]. It is generally recommended that the epoxide be isomerised to a mixture of keto compounds [473], or that the ring should be opened with boron trifluoride-methanol reagent to a mixture of methoxy-hydroxy derivatives [481,833] or with lithium aluminium hydride to hydroxy derivatives followed by trimethylsilylation [940], for identification by GC-MS. MS was used to study the incorporation of into the oxirane ring of 9,10-epoxyoctadecanoic acid in wheat tissues [488]. If derivatization is undesirable, more useful spectra are obtained with chemical ionisation [474,717]. 

N-methyltryptamine (dipterine) has been converted into its Grignard derivative and oxidized in situ with ethereal ferric chloric to yield dl- along with a trace of meso-chimonanthine. These were the expected products since they were produced under conditions where no possibility for hydrolytic ring opening was provided. In a different approach, N-methoxycarbonyl 3-2 -aminoethyloxindole was dimerized by means of iodine in tetra-hydrofuran to furnish two isomeric dimers which were reduced separately with lithium aluminium hydride which converted the — NHCOOMe to — NHMe and the oxindole to the carbinolamine. 

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