Cyclic secondary alcohol

The oxidation of alcohols by treatment of their corresponding chloroform-ates with DMSO and triethylamine has been reported by Barton. Preliminary results indicate this to be a useful method for preparation of aldehydes but cyclic secondary alcohols are converted to ketones in relatively low yields. 

In addition to simple halides, the method was used to prepare chol-esteryl iodide (30%) and cyclohexyl iodide (34%) from the corresponding alcohols, thus demonstrating the applicability of the reaction to cyclic secondary alcohols. An early adaptation to carbohydrates was reported by Lee and El Sawi (75). They claimed that treatment of l,2 5,6-di-0-isopropylidene-D-glucofuranose (49) with triphenylphosphite methiodide... 

In comparison to the N- and S-counterparts, alkoxides possess lower nucleophilicity. Therefore, the reductive elimination process to form the C—O bond is much slower than those to form C— N and C—S bonds [103]. Palucki, Wolfe and Buchwald developed the first intramolecular Pd-catalyzed synthesis of cyclic aryl ethers from o-haloaryl-substituted alcohols [104]. For example, 3-(2-bromophenyl)-2-melhyl-2-butanol (91) was converted to 2,2-dimethylchroman (92) under the agency of catalytic Pd(OAc)2 in the presence (S)-(-)-2,2 -bis(di-p-tolylphosphino)-l,l -binaphthyl (Tol-BINAP) as the ligand and K2C03 as the base. The method worked well for the tertiary alcohols, moderately well for cyclic secondary alcohols, but not for acyclic secondary alcohols. 

As shown in Figure 1.10, kinetic resolution of racemic acyclic and cyclic secondary alcohols can be achieved by the BINAP-Ru method with up to 74 1 differentiation between the enantiomers [139]. An application includes a practical resolution of a racemic 4-hydroxy-2-cyclopentenone, an important prostaglandin building block that is achievable on a multi-kilogram scale. Racemic methyl a-(hydroxyethyl)acrylate is reduced by hydrogen... 

Clearly such a method is of limited preparative value, but an important exception is the oxidation of cyclic secondary alcohols which on oxidation with nitric acid give good yields of dicarboxylic acids by way of the intermediate cyclic ketone, e.g. adipic acid from cyclohexanone, Expt 5.123. 

Answer Vl-I is a cyclic secondary alcohol (2-propylcydo-pcittauol). 

In the hydrogenation of racemic allylic alcohols catalyzed by a chiral Rh catalyst, at most, 20 1 discrimination has been attained for some acyclic substrates. BINAP-Ru complexes have been used for kinetic resolution of chiral acyclic and cyclic secondary alcohols with up to 74 1 differentiation between the enantiomeric alcohols (equation 15). ... 

A less complete oxidation of hexa-hydro benzene than that represented by the relationship of the tri-ketone compound above yields a series of cyclic secondary alcohols some of which are natural substances. Their relationship to hexa-hydro benzene is as follows ... 

Dimethyl sulfoxide oxidizes primary allylic alcohols in preference to cyclic secondary alcohols [1018] and is suitable for oxidations of sterically hindered alcohols in high yields [1009, 1139] (equation 263). 

Derivation (1) A mixture of three isomeric (o-, m-, and p-) cyclic secondary alcohols made by the hydrogenation of cresol, (2) catalytic oxidation of methylcyclohexane. 

Within the field of proline-derivative it should be mentioned that the (2S,4R)-4-hydroxy-N-methylproline derivative 27 supported on JandaJel (a more swellable version of crosslinked PS) was employed by Janda and coworkers to catalyze the kinetic resolution of some cyclic secondary alcohols (Scheme 8.15) [47]. In tlie presence of 0.15 mol equiv of the catalyst, the benzoylation of racemic trcms-2-... 

BzCl or BZ2O, Pyr, 0 C. Benzoyl chloride is the most common reagent for the introduction of the benzoate group. Reaction conditions vary, depending on the nature of the alcohol to be protected. Cosolvents such as CH2CI2 are often used with pyridine. Benzoylation in a polyhydroxylated system is much more selective than acetylation. A primary alcohol is selectively protected over a secondary allylic alcohol, and an equatorial alcohol can be selectively protected in preference to an axial alcohol," but this has been shown to be solvent dependant in some cases." A cyclic secondary alcohol was selectively protected in the presence of a secondary acyclic alcohol. ... 

Chhikara and coworkers [17] have reported that ionic liquids are excellent reaction media for the oxidation and dehydrogenation of steroids with IBX. In a systematic study, they investigated the efficacy of the oxidation of cyclic secondary alcohols with IBX in [bmun][Br] (Scheme 14.17). They noticed that the nature of the products formed is influenced by several factors such as the relative ratio of IBX, quantity of IBX, and temperature of the reaction. For example, when 1.2 eq. of IBX was... 

Table 11.1-21. Lipase-catalyzed enantiomer-differentiating acylation of racemic cyclic secondary alcohols in organic solvents (CCL Candida cylindracea lipase, PSL Pseudomonas sp. lipase, CAL-B Candida antarctica B lipase, PPL pig pancreas lipase, PCL Pseudomonas cepacia lipase, LIP Pseudomonas sp. lipase-Toyobo, ASL Alcaligenes sp. lipase, PFL Pseudomonas fluorescent lipase, BSL Burkholderia sp. lipase, CRL Candida rugosa lipase, MML Mucor miehei lipase).

Table 11.1-21 lists cyclic secondary alcohols that have been synthesized by lipase-catalyzed enantiomer-differentiating acylation (1-129). The compounds that have been obtained by the alternative route of hydrolysis are listed in Table 11.1-16. The complementary nature of the two routes is obvious. For the series of the glycals 9-15, Pseudomonas cepacia lipase-catalyzed acylation works with good to high enantiomer selectivity and yield. myo-Inositol derivatives 17 and 18 may be prepared enantiomer-...

Among the many other cyclic secondary alcohols that have been obtained by lipase-catalyzed enantiomer-selective acylation with high enantiomeric excess are aminofunctionalized cycloalkanols (40, 45-62, 75), bicyclo[3.3.0]octanols (78, 84-86), different types of tri- and tetracyclic alcohols (96-104), substituted indanols (87-94,123), hydroxy lactams (106,109-112) and brominated cyclohexenol derivatives (74, 77,124-127) (Table 11.1-21). 

Table 4.10 Guanidine mediated asymmetric silylation of cyclic secondary alcohols...

The first compound is an ester derived from a cyclic secondary alcohol that could be made from the corresponding enone by asymmetric reduction. 

Conversion of Alcohols to Chlorides. A variety of trans-/3-substituted cyclic secondary alcohols have been stereoselec-tively chlorinated to either the corresponding cw-chloride or trans-chloride in good to excellent yields the stereochemical outcome is determined by the size of the ring and the nature of the /3-substituents, especially the electronegativity of the substituent atom. When intermolecular Sn2 reaction occurs, the reaction provides dy-chloride product when intramolecular Sn2 reaction occurs, a three-member ring is formed as intermediate, followed by nucleophilic attack to give frawy-chloride product (eq 45). ... 

This enzyme catalyses reactions with primary alcohols, secondary alcohols, or semiacetals. The enzyme is animal tissue, unlike that in yeast, also catalyses reactions with cyclic secondary alcohols. This enzyme has been called aldehyde reductase. 

Several crude lipase preparations are available from the yeasts Candida lipolytica, C. antarctica (CAL), and C. rugosa (CRL, syn. C. cylindracea). The latter enzyme, the three-dimentional structure of which has been resolved by X-ray analysis [333], has been frequently used for the resolution of esters of secondary alcohols [401-406] and, to a lesser extent, for the resolution of a-substituted carboxylates [407,408]. The CRL preparations from several commercial sources which contain up to 16% of protein [409] differ to some extent in their activity but their selectivity is very similar [410]. As CRL is able to accommodate relatively bulky esters in its active site, it is the lipase of choice for the selective hydrolysis of esters of cyclic secondary alcohols. To illustrate this point, some representative examples are given below. 

Also oxidation of linear and cyclic secondary alcohols and benzylic alcohols to the corresponding carbonyl compounds under microwave irradiation conditions can be achieved. 

Carbonyl-ene reactions represent one type of important cycloaddition reactions for the synthesis of homoallylic alcohols. Titanium compounds have been extensively applied as the Lewis acids for this type of transformation. Both inter and intramolecular carbonyl-ene reaction could be catalyzed by Ti(O Pr)4 or TiCU, giving the corresponding acyclic or cyclic secondary alcohols with high yields [126] (Scheme 14.46). 

A similar rate law is observed in reaction of cyclic secondary alcohols by [Cu(0H)2H4Te06], where the rate is independent of ring size C5-C7. This points to rate-determining O-H rather than C-H bond scission in the proposed [CuOH2TeOsROH] complex. The reaction is catalyzed by OSO4. 

---