Cyclo pentanol

Ein Beispiel fur die TiFFENEAU-Umlagerung ist die Ringerweiterung von 1 -Aminomethyl-cycloalkanolen durch Einwirkung von salpetriger Saure zu cyclischen Ketonen. Nach Versuchen von Arnold (6) mit 1 -Aminomethyl- [14C]-cyclo-pentanol-1 lmd - -Aminomethyl-[14C]-cyclo-hexanol-1 erscheint nach der Umlagerung das markierte Atom in der 2-Stellung des Ketons. 

Silyl protecting groups are the gold standard for the protection of alcohols.234 Novel photochemically removable protection groups for alcohols have been developed by Brook et a/.23S and Pirrung et al,236 For instance, cyclo-pentanol can be reacted with tris(trimethylsilyl)chlorosilane 53 in the presence of a mild base to yield the protected silyl ether 54. The protection group can be removed conveniently upon UV irradiation or by the use of Bu4NF (Scheme 12). 

The observation that fram-2-hydroxy-l-cyclopentanecarboxamide does not react with aldehydes or ketones was used in the synthesis of stereohomo-geneous cis cyclopentane-fused oxazinones and c -2-aminomethyl-l-cyclo-pentanol derivatives. The cumbersome separation of the cis- and tram-2-hydroxy-l-cyclopentanecarboxamides can be avoided, because only the cis isomer forms the oxazinone ring (81S628 83T1829). 

Grey and Vega (161) have demonstrated the use of the TRAPDOOR experiment for measuring the 27Al quadrupole coupling constant in zeolites and applied it to studies of trimethylamine in zeolites. In other spectroscopic work, Fripiat and co-workers (162) used REDOR and various other NMR methods to characterize acid sites in zeolites treated with ammonia. Ernst and Pfeiffer (163) have reported a 13C MAS NMR study of the reactions of methanol and ammonia to make methylamines in zeolite HZSM-5. We reported NMR evidence of the synthesis of cyclopentylamine from cyclo-pentanol and ammonia on zeolite CsX (102). 

Heptanol, 2-methyl-3-hexanol, 2,4-dimethyl-3-pentanol, cyclo-pentanol, cyclohexanol, cyclo-heptanol, cyclooctanol, cis-and trans-2-methylcyclohexanol, cis- and trans-4-tert-butyl-cyclohexanol ai2o3 180-210 94... 

Alkynes can also be used as radical acceptors for the generation of cyclo-pentanols bearing an exocyclic alkene, but in nearly all cases the yields are modest compared with those obtained in the related cyclisations of alkenes. Activation of the alkynes by electron-withdrawing groups or silyl substituents leads to more efficient 5-exo-dig ring closure.55... 

When we discussed reduction of cyclopen ten one to cyclo-pentanol, we suggested that conjugate addition of borohydride must occur before direct addition of borohydride in other words, this scheme must be followed. 

As part of the synthesis of 1,6-dimethyldodecahedrane 108), an interesting case has been reported 109) of cyclization of a polycyclic diketone in which two new cyclo-pentanol rings were formed, as illustrated by the partial structures shown below. X-ray crystallographic analysis showed that conformational factors were particularly favorable for this unique result. 

Both exo- and endo-cyclic alicyclic and heterocyclic ketones have been reduced. Important examples are found in the preparations of cyclo-pentanol (95%), cycloheptanol (92%), /S-pyridylmethylcarbinol (85%), and l-alkyl-4-piperidinols (90%). A comparison of four reagents—sodium and alcohol, lithium aluminum hydride, hydrogen and Raney nickel, and hydrogen and copper-chromium oxide—has been made in the preparation of methyl cyclopropylcarbinol. The last method is superior for the preparation of this compound (SH)%). ... 

Problem 21.25 Outline all steps in a possible laboratorv synthesis of each ylide and each carbonyl compound in the preceding problem, starting from ben/cne, toluene, alcohols of four carbons or fewer, acetic anhydride, triphcnylphosphine, and cyclo-pentanol, and using any needed inorganic reagents. 

Samarium-based hydroxy-directed cyclopropanation was useful in obtaining the requisite cyclo-pentanol 136 to prepare several bicyclo[3.1.0]hexane-fused 2, 3 -modified dideoxycarbocyclic nucleosides. ... 

The cathodic cyclization of 5-enones leads regio- and stereoselectively to cyclo-pentanols (Eqs. 22, 23) [161]. The reduction of the non-conjugated dienone affords in a tandem reaction a bicyclic alcohol (Eq. 24) [162]. 

Two peaks were observed up to pressures of 1.5 kbar at 2 kbar, only one DSC peak was observed. The lower temperature peak was due to a solid-solid phase transformation, whereas the other peak was caused by the fusion of the compound. Similar studies were made using cyclopentanone, cyclo-pentanol, and cyclohexanone up to 3 kbar applied pressure (136). 

Squamulosone (77) was treated in the fungus M. plumbeus ATCC 4740 to give not only cyclo-pentanol derivatives (89, 90) but also C12 hydroxylated products (91-93) (Collins et al., 2002b) (Figure 20.31). 

MethylUter der 1.2.3-TrimethyI-cyclo pentanol-(3)-o ibonsaiiie-(l) 10,16. -[l-OJT-oyolohexyI]-bntteraaiire 10II11. -[2-Oxy-oyolohexyl]-isobiittersitiire... 

An interesting product from 2-cyclopropylethylamine is cyclo-pentanol, which is believed to result from irreversible migration of the ring to C(i) (reaction 28), although the reactions are complicated by... 

C19H2 ft03, 2-(2-Hydroxyethyl)-2-methyl-3-(6-methoxy-2-naphthyl)cyclo-pentanol, 44B, 140... 

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