Cyclohexylidene

Cyclohexylidenes are slightly harder to cleave than acetonides... 

The cyclohexylidene ketal, prepared from a catechol and cyclohexanone (AI2O3/ TsOH, CH2CI2, reflux, 36 h), is stable to metalation conditions (RX/BuLi) that cleave aiyl methyl ethers. The ketal is cleaved by acidic hydrolysis (coned. HCl/ EtOH, reflux, 1.5 h, 20°, 12 h) it is stable to milder acidic hydrolysis that cleaves tetrahydropyranyl ethers (1 AHCl/EtOH, reflux, 5 h, 91% yield). ... 

Cyclohexylidene fulvene [3141-04-6] M 134.2. Purified by column chromatography and eluted with -hexane [Abboud el al. J Am Chem Soc 109 1334 1987]. 

Acetonide (Isopropylidene), 207 Cyclopentylidene, 215 Cyclohexylidene, 215 Cycloheptylidene, 215 Benzylidene, 217... 

Cyclopentylidene Ketal, i Cyclohexylidene Ketal, ii Cycloheptylidene Ketal, iii... 

Methylene, 287 Pivaldehyde Acetal, 289 Acetonide, 289 Cyclohexylidene. 289 Diphenylmethylene, 289 Ethyl Orthoformate, 290 Diisopropylsilylene Derivative, 290... 

A/-5-Chlorosalicylidene, 589 A/-(5-Chloro-2-hydroxyphenyl)phenylmethylene, 589 A/-Cyclohexylidene, 589 A/-f-Butylidene, 589... 

For the related cyclohexylidene acetal cyclohexanone, TsOH, benzene, reflux 40 h with Soxhlet containing 4A molecular sieves, 82% yield. 

Dipolar cycloadditkm reactions of nitrones to olefins, 46, 1,3-Dipolar cycloadditions with 3-phenylsydnone, 45, 98 Dispiro[5 1 5 l]tetradecane-7,14-dione, photolysis to cyclohexylidene-cyclohexane, 47, 34 preparation from cyclohexanecarbonyl chlonde and triethylamine, 47,34 Displacement of bromine from 1-bromo-2-fluoroheptane to give 2-fluoro-heptyl acetate, 46, 37... 

Henry reaction of the (V-acetyl-D-glucosamine derived nitrosugar 1 with 2,3-O-cyclohexylidene-D-glyceraldehyde (2) furnishes a single product 3 in 85-90% yield7. 

Cyclohexanone, 23,35 Cyclohexene oxide, 137 Cyclohcxyl methyl ether, 137 l-Cydohexyl-2-methylpropene, 68-9 ( )-l-Cyclohexyl-2-trimethyl ilylethene, 12 (Z)-l-Cyclohexyl-2-trimethylsilylelhene, 12 l-Cydohcxyl-2-trimethylsilylethyne, 12 (2-Cyclohexylidene-eihyl)trimethylsilane, 29 Cyclopentadec-2-ynone, 48 Cydopentadiene, 25 Cyclopentanone, 72 Cyclopentenones, 15 Cyclopropanone, 133... 

Das aus (-)-Menthol hergestellte chirale Hydrid liefert in erster Linie mit zweizahnigen Substraten [fi-Amino- ketone, En-(2)-in-(4)-ole (s.S. 74)] gute optische Ausbeuten1. Als chirale vie. Diole werden Zucker-2,1 und Terpen-Derivate wie cis- und rrans-Pinandiol-(2,3)4 verwendet. Von den Zucker-Derivaten hat sich der Kom-plex mit 3-0-Benzyl-l,2-0-cyclohexyliden-a-D-glucofuranose am besten bewahrt2,5 (Vorschrift S. 74). 

Hydroxy-2-cyclohexyl-propansaure-nitrH Zu 2,5 g (0,065 Mol) Natriumboranat in 25 ml Athanol wird unter Riihren bei 0 eine Losung von 12 g (0,065 Mol) Cyclohexyliden-cyan-essigsaure-athylester in 25 ml Athanol getropft. Man riihrt 18 Stdn. bei 20° nach, verdiinnt mit ges. Natriumchlorid-Losung, extrahiert mit Diathylather und Benzol, dampft nach Trocknen die Solventien ab und destilliert den Riickstand Ausbeute 5 g (54% d.Th.) Kp .s 115-117". 

Allyl- -diathylester 204 Allyl-(2-methyl-allyl)- -diathylester 202 -amid-nitril (2,2-disubst.) 113 Amino- -diathylester 613 Benzyl- -diathylester 204, 208, 210 Benzyl- -dinitril 559 Benzyliden- -diathylester 208, 210 Benzyliden- -diathylester-nitril 206 Benzyliden- -dinitril 559, 643 ter.-Butyl- -nitril 114 Cyclohexyl- -athylester-nitril 206 Cyclohexyl- -diathylester 204 Cyclohexyl- -dinitril 559 Cyclohexyliden- -athylester-nitril 206 Cyclohexyliden- -dinitril 559 (1-Cyclopropyl-athyliden)- -dinitril 666 Diathyl- -amid-nitril 113 -diester 640... 

The two -OH groups in l,2 5,6-di-0-cyclohexylidene-wii/o-inositol and its di-O-isopropylidene analog are trans. The X-ray crystal structure of the latter compound suggests that the ring is in a skew conformation with the 0-3 and 0-4 -OH groups both in ax positions, but NMR studies and ab initio calculations indicate that a mixture of the skew and chair conformations, with 0-3 and 0-4 both in eq positions, is present. Formation of a dibutylstannylene acetal presumably locks these two compounds in the latter conformation. 

Abbreviations Cy, cyclohexylidene DNP, 2,4-dinitrophenyl Py, pyridine TIPS, -(PrOjSiOSilPrOj- rac., racemate r.t., room temperature A, reaction in dichloromethane B, reaction in benzene D, reaction in diglyme T, reaction in toluene. Yields are described in the order of products, drawn from the left to the right. The sum of the last two compounds. Inserted as a reference reaction. 

Although menthyl esters, especially 19, are most often used to prepare sulfoxides, esters derived from optically active alcohols other than menthol have been prepared . Ridley and Smal prepared arenesulfmic esters of 1,2 5,6-di-O-cyclohexylidene-a-D-glucofuranose. Unfortunately, these diastereomers were oils, except for the mesityl derivative, with the major epimer having configuration R at sulfur and so they offered no advantage over the menthyl esters. Separation of the epimers by chromatography failed. 

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