Cyclohexyl chloroformate

R = (-)-trans-2-(a-cumyl)cyclohexyl chloroformate, TIPS = triisopropylsilyl,... 

The 209D diastereomer (+ )-590 has also been made by Comins and Zhang (Scheme 78) 466,467). After 77-acylation of the 4-methoxypyridine 591 with (1 S,2R,4S)-4-isopropyl-2-( 1 -methyl-1 -phenylethyl)cyclohexyl chloroformate, the resulting pyridinium salt was intercepted with hexylmagnesium chloride to give the optically active enaminone 592. Removal of the chiral auxiliary and A -alkylation with (Z)-l,3-diiodopropene yielded 593, thereby setting the scene for a novel anionic... 

Cyclohexyl-2-butenoicacid Cyclohexyl chloroformate Cyclohexylcyclohexane Cyclohexyldiethylamine... 

The reaction between ethyl Hthiopropiolate and the N-acylpyridinium salt formed by reaction of 4-methoxy-3-methyl-5-(triisopropylsilyl)pyridine 2363 with (+)-frafis-2-(a-cumyl)-cyclohexyl chloroformate (TCC chloro-formate) was the starting point in the synthesis of (-l-)-aUopumihotoxin 267A (1718) by Comins et al. (Scheme 301). The dihydropyridone product (—)- 2364 was obtained diastereoselectively (>96%) before hydrogenation to the saturated ester (+)-2365. However, some epimerization of the methyl substituent was apparent after cleavage of the TCC carbamate with lithium methoxide and cyclization to the indolizidinone (—)-2366 (dr 8 1). Acetoxylation at C-8 with lead tetraacetate was stereoselective, and introduced the acetate from the axial direction, possibly by stereoelec-tronicaUy-controUed intramolecular transfer of acetate from a lead—enol intermediate. The acetoxy product (—)-2367 was protodesilylated with formic acid, after which a one-pot tandem reduction with K-Selectride followed by hthium aluminum hydride gave diol (- -)-2368 with complete... 

N-cyclohexyl-1-chlorophthalimlde (250 g) was dissolved in glacial acetic acid (2.5 8),concentrated hydrochloric acid (555 ml) and tin (27B g) were added and the suspension was heated on a steam bath for 16 hours. The cooled solution was filtered and concentrated to dryness in vacuo to give a white solid. This solid was dissolved in water and the precipitated oil extracted with chloroform. The chloroform solution was dried and concentrated in vacuo to give a solid which, after recrystal I izat ion, yielded 5-chloro-2-cyclohexylisoindolin-1-one (43%), MP 140°Cto 142°C. 

Addition, chloroform, to olefins to form 1,1,3 tnchloroalkanes, 46, 106 chlorosulfonyl isocyanate to isobutylene to give 0-isovaleiolactam-N-sulfonyl chloride, 46, SI cyclohexyl amine to silicon tetraiso-cyanate, 46, 69... 

B. Cyclohexanol from cyclohexyl methyl ether. In a 25-mL, oven-dried, round-bottomed flask is placed 1.722 g. (0.0151 mole) of cyclohexyl methyl ether (Note 7). The flask is purged with nitrogen and sealed with a rubber septum. By means of oven-dried syringes, 4 ml, of chloroform (Note 8), 0.5 g. (0.5 ml., 0.006 mole) of pyridine (Notes 8 and 9), and 4.8 g. (3.5 ml., 0.024 mole) of... 

A number of nonnatural amino acids were resolved into individual enantiomers on 0-9-(2,6-diisopropylphenylcarbamoyl)quinine-based CSPby Peter and coworkers [48,90,113,114] after derivatization with Sanger s reagent, chloroformates (DNZ-Cl, FMOC-Cl, Z-Cl), Boc-anhydride, or acyl chlorides (DNB-Cl, Ac-Cl, Bz-Cl). For example, the four stereoisomers of P-methylphenylalanine, P-methyltyrosine, P-methyltryptophan, and P-methyl-l,2,3,4-tetrahydroisoquinoline-3-carboxylic acid could be conveniently resolved as various A-derivatives [113]. The applicability spectrum of cinchonan carbamate CSPs comprises also P-amino carboxylic acid derivatives, which were, for example, investigated by Peter et al. [114]. A common trend in terms of elution order of DNP-derivatized P-amino acids was obeyed in the latter study On the utilized quinine carbamate-based CSP, the elution order was S before R for 2-aminobutyric acid, while it was R before S for the 3-amino acids having branched R substituents such as wo-butyl, iec-butyl, tert-butyl, cyclohexyl, or phenyl residues. 

The UV spectra of 1,2-thiazetidinone oxides have been recorded by Beeken and Korte. Measured in cyclohexane or chloroform, the N-substituted cyclohexyl- (35), phenyl-, and aryl-substituted 4,4-bisphenyl-l,2-thiazetidin-3-one 1,1-oxides showed an average absorption band at = 240 nm... 

To a 250 ml three-neck round bottom flask was added 10.0 g (32.01 mmol) of (8p)-l-isopropyl-6-methylergoline-8-carboxylie acid, 4.43 g (32.1 mmol) of potassium carbonate and 200 ml of N,N-dimethylformamide. The mixture was refluxed and 25 ml of a distillate was collected. The remaining solution was cooled in an ice bath, and then with an acetonitrile/carbon dioxide bath which lowered the temperature of the reaction mixture to about -45°C this mixture was added 4.59 g (33.62 mmol) of isobutyl chloroformate dropwise. The resulting mixture was stirred for approximately 5 min and 3.49 g (35.21 mmol) of cyclohexylamine was added. The reaction mixture was allowed to warm to room temperature and stirred for approximately 19 h. To the mixture was added 500 ml of ice water containing 25 ml of concentrated ammonium hydroxide. The mixture was cooled and the precipitated solid was collected by vacuum filtration. The resulting solid was washed with water and dried in vacuo to provide 10.13 g (yield 76.8%) of the (8P)-N-cyclohexyl-l-isopropyl-6-methylergoline-8-carboxamide having a purity of 92.3%. 

The product was extracted into chloroform, dried over Na2S04, filtered, and concentrated to a foam. Recrystallization from 1 4 (v/v) methylene chloride/hexane gave 5.0 g (100%) of the desired H-L-(4-thiazolyl)Ala amide of (2S,3R,4S)-2-amino-l-cyclohexyl-3,4-dihydroxy-6-methylheptane as a fluffy white solid, melting point 111°-112°C. 

Diaryl tellurium trifluoroacetimides and sulfonimides react with l,3-dioxo-5,5-dimeth-ylcyclohexane in chloroform at 20° to produce diaryl 2,6-dioxo-4,4-dimethyl-cyclohexyl-idene telluriums3. 

Diasteriomers were isolated by reacting the Step 5 product mixture with (—)-8-phenylmenthol chloroformate. The diasteriomers were separated by flash chromatography over silica gel using chloroform/hexanes/diethyl ether (3 2 1), and (lS,2R,5S)-5-methyl-2-(l-methyl-l-phenylethyl)-cyclohexyl-9-(3-bromo-4-fluoro phenyl)-8-oxo-2,3,5,7,8,9-hexahydro-4H-pyrano[3,4-b]thieno[2,3-e]pyridine-4-carboxylate 1,1-dioxide isolated (3). 

Several complexes have beeai found to be dimeric. Infrared spectroscopy shows that the CuNCS(L) complexes (L = py, 2- or 4-picoline, 3,5-lutidine, or quinoline) contain bridging thiocyanato groups (332). The mass spectra of CuX P(cyclohexyl)3 complexes (X = Cl, Br, I) show no peaks of higher mass than those corresponding to dimeric molecules, and the far-infrared spectrum of the chloro complex indicates that they are dimeric with halo bridges (248). Triphenylphosphine reacts with copper(I) trifluoroacetate in dichloromethane to give [Cu(02C CF3)(PPh3)]2 which is dimeric in chloroform but partially dissociated in dichlorobenzene (107). 

---