Camphor, 3-hydroxy

Calcium D-galactonate, I, 70 Calcium D-gluconate, III, 141, 142, 149, 152, 155, 156, 161 IV, 331 Calcium hypochlorite, III, 165 Calcium 2-keto-D-gIuconate, III, 148, 155 Calcium 5-keto-D-gluconate, III, 156 Calcium lactobionate, calcium bromide double salt, III, 155 Calcium Ievulinate, IV, 311 Calcium maltobionate, III, 161 Calcium D-mannonate, III, 152 Calcium pectate, I, 334 Calcium D-rhamnonate, III, 144 Calcium salts, in preparation of aldonic acids with NaCN, I, 23 Calcium vicianobionate, III, 154 Calcium D-xylonate, III, 155 Camphor, optically active, formed from inactive (racemic) camphor carboxylic acid in the presence of quinine, quinidine or nicotine, V, 53 Camphor carboxylic acid. See Camphor. Camphor, 3-hydroxy-, IV, 89 Camphorquinone, phytochemical reduction of, IV, 89... 

Ordinary commercial camphor is (-i-)-cam phor, from the wood of the camphor tree. Cinnamonum camphora. Camphor is of great technical importance, being used in the manufacture of celluloid and explosives, and for medical purposes, /t is manufactured from pinene through bornyl chloride to camphene, which is either directly oxidized to camphor or is hydrated to isoborneol, which is then oxidized to camphor. A large number of camphor derivatives have been prepared, including halogen, nitro and hydroxy derivatives and sulphonic acids. 

Supplement 1950 1505-1591a acid, 269. Hydroxy-carbonyl sulphonic acids Camphor-sulphonio acid, 345. Carboxylic-sulphonic acids, 368. Se and Te acids, 422. 

Several methods for asymmetric C —C bond formation have been developed based on the 1,4-addition of chiral nonracemic azaenolates derived from optically active imines or enamines. These methods are closely related to the Enders and Schollkopf procedures. A notable advantage of all these methods is the ready removal of the auxiliary group. Two types of auxiliaries were generally used to prepare the Michael donor chiral ketones, such as camphor or 2-hydroxy-3-pinanone chiral amines, in particular 1-phenylethanamine, and amino alcohol and amino acid derivatives. 

In an early attempt to synthesise camphor, dlol (1) was an important intermediate. We shall want to disconnect the ring from the chain, so a preliminary disconnection of a methyl group gives an ct-hydroxy ketone (2) which can be made from ketone (3) and an acyl anion equivalent. 

In THF at -20°C the N-trimethylsilylated 2-pyrrolidinone 388 is converted by LDA into the a-anion which, on reaction with 1949 and subsequent acidification with AcOH, gives 43% 3-hydroxy-2-pyrrolidinone 1962 [150]. Lithium enolates of ketones such as camphor react with BTSP 1949 to give >95% of a mixture of exo-and mdo-2-hydroxycamphor [151]. Lithiated methyl heterocycles such as lithiated 2-methylpyridine 1963 are converted into mixtures of the 0-SiMe3 1964 and C-SiMe3 1965 compounds and C-methylated compounds such 1966 [152]. 2-Lithioto-luene 1967 is oxidized by 1949 into 1968 [140, 145] (Scheme 12.42). 

Figure I. Crystal structure of lTa.ns-4 -hydroxy- N-methyl-4-stilbazoIium (+)-camphor-...

However, most asymmetric 1,3-dipolar cycloaddition reactions of nitrile oxides with alkenes are carried out without Lewis acids as catalysts using either chiral alkenes or chiral auxiliary compounds (with achiral alkenes). Diverse chiral alkenes are in use, such as camphor-derived chiral N-acryloylhydrazide (195), C2-symmetric l,3-diacryloyl-2,2-dimethyl-4,5-diphenylimidazolidine, chiral 3-acryloyl-2,2-dimethyl-4-phenyloxazolidine (196, 197), sugar-based ethenyl ethers (198), acrylic esters (199, 200), C-bonded vinyl-substituted sugar (201), chirally modified vinylboronic ester derived from D-( + )-mannitol (202), (l/ )-menthyl vinyl ether (203), chiral derivatives of vinylacetic acid (204), ( )-l-ethoxy-3-fluoroalkyl-3-hydroxy-4-(4-methylphenylsulfinyl)but-1 -enes (205), enantiopure Y-oxygenated-a,P-unsaturated phenyl sulfones (206), chiral (a-oxyallyl)silanes (207), and (S )-but-3-ene-1,2-diol derivatives (208). As a chiral auxiliary, diisopropyl (i ,i )-tartrate (209, 210) has been very popular. 

Davis et al.111 developed another method for reagent-controlled asymmetric oxidation of enolates to a-hydroxy carbonyl compounds using (+)-camphor-sulfonyl oxaziridine (147) as the oxidant. This method afforded synthetically useful ee (60-95%) for most carbonyl compounds such as acyclic keto esters, amides, and a-oxo ester enolates (Table 4-20). 

Holton s Construction of the Polycyclic Ring. In Holton s synthesis,23 compound 97, which can be prepared from camphor derivatives, is the starting material. Hydroxy-directed epoxidation of compound 97 gives unstable compound 98, which fragments in situ to provide compound 99, thus furnishing the AB skeleton of taxol (Scheme 7-31).24... 

This enzyme [EC 1.14.15.1], also known as camphor 5-exo-methylene hydroxylase, and cytochrome P450-cam, catalyzes the reaction of (+)-camphor with putidare-doxin and dioxygen to generate (-F)-exo-5-hydroxy-camphor, oxidized putidaredoxin, and water. A heme-thiolate acts as a cofactor. The enzyme can also utilize ( )-camphor as a substrate, and l,2A-campholide will result in the formation of 5-exo-hydroxy-l,2-campholide. V. Ullrich W. Duppel (1975) The Enzymes, 3rd ed., 12, 253. 

Hydroxy acids provide characteristic mono or diol synthons whereas amino acids are the natural source for 1,2-amino alcohol fragments. A stereogenic center in either configuration, with methyl brandling, may be obtained from (S)-3-hydroxy-2-methylpropanoic acid, whereas quaternary dimethyl-substituted carbons with adjacent stereogenic centers are available from the degradation of camphor or a-pincnc. 

Camphor- 10-sulfonic acid, 62 (S)-2-(l-Hydroxy-1-methylethyl)-pyrrolidine, 146 a-Methylbenzylamine, 185 Quina alkaloids, 264 Cycloaddition reactions 2-Oxazolidones, chiral, 225 Cyclopropanation Diiodomethane-Diethylzinc, 276 Simmons-Smith reagent, 275 Deprotonation Lithium amides, chiral, 159... 

Other methods to form carboxylic acids Cyanotrimethylsilane, 87 a-Substituted carboxylic acids (see also Amino acids, Halo carbonyl compounds, Hydroxy acids) Camphor-10-sulfonic acid, 62 Chiral compounds Alcohols... 

Camphor-10-sulfonic acid, 62 (S)-2-( 1-Hydroxy-1-me thyl-ethyl)pyrrolidine, 146 Amines... 

From hydroxy acids or acyl derivatives Camphor-10-sulfonic acid, 62 Molybdenum carbonyl, 194 Sodium iodoacetate, 149 Thiophenol, 297... 

Borneol (Also called Bornyl Alcohol, Baras Camphor, Borneo-Camphor, 2-Camphanol, d--Camphyl Alcohol, 2-Hydroxy-Camphane or Sumatras Camphor), C10H,7OH mw 154.24,... 

The authors reported the chiral separation of proline and thereonine amino acid up to 20 and 6g, respectively, in a single run. Micropreparative resolution of lecucine was presented. The resolution was discussed with respect to the degree of sorbent saturation with copper(II), elution rate, eluent concentration, temperature, and column loading condition [16]. Weinstein [74] reported the micropreparative separation of alkylated amino acids on a Chiral ProCu column. In another article, a preparative chiral resolution of 3-methylene-7-benzylidene-bicyclo[3.3.1]nonane was achieved on 7.5% silver(I)-d-camphor- 10-sulfonate CSP [75]. Later, Shieh et al. [71] used L-proline-loaded silica gel for the chiral resolution of (ft,5 )-phcnylcthanolaminc as the Schiff base of 2-hydroxy-4-methoxyacetophenone. Gris et al. [76] presented the preparative separations of amino acids on Chirosolve L-proline and Chirosolve L-pipecolic acid CSPs. 

An unusual cyclopropanation of 9-bromocamphor derivatives (5) to a 7-spirocyclo-propyl camphor derivative (6) has been realized by the action of potassium r-butoxide (or sodium hydride) in warm DMSO (Scheme 8).29 The exo-hydroxy group and a nonhydrogen endo-substituent at C(2) were proven to be essential structural elements, and the solvent DMSO the sole effective reaction medium. 

Asymmetric Baylis-Hillman reactions using sugar acrylates have been reported to proceed with moderate diastereoselectivity (5-40% ee) [23]. The reaction of camphor-based chiral acryloylhydrazides with aldehydes in the presence of DABCO afforded /1-hydroxy-a-methylene carbonyl derivatives in 68-92% yield with high diastereoselectivity (up to 98% de) [24]. Both diastereomers could be selectively obtained simply by changing the solvent. 

Sato and coworkers have reported an asymmetric synthesis of Baylis-Hillman-type allylic alcohols 48, 49 via a chiral acetylenic ester titanium alkoxide complex (Scheme 9) [41]. These reactions rely on the use of the novel acetylenic ester titanium alkoxide complex 44 with a camphor-derived chiral auxiliary. Optically active, stereodefined hydroxy acrylates 46, 47 were obtained in high yields and with excellent regio- and diastereoselectivities. The chiral auxiliary was subsequently cleaved off by alcoholysis. 

---