2- cyclopropylcarbinol

Scheme 12.2 shows various types of alcohols that are most susceptible to Mn02 oxidation. Entries 1 and 2 illustrate the application of MnOz to simple benzylic and allylic alcohols. In Entry 2, the Mn02 was activated by azeotropic drying. Entry 3 demonstrates the application of the reagent to cyclopropylcarbinols. Entry 4 is an application to an acyloin. Entry 5 involves oxidation of a sensitive conjugated system. 

Oxidative rearrangement of the tertiary-cyclopropylcarbinol 262 using PCC leads to the / ,y-unsaturated ketone 263 and halide 264 [149], (Scheme 104)... 

Cyclopropylcarbinols. Treatment of cyclopropylcarbinols 15 (R = Ph, C-C3H5) with trifluoroacetic acid in dichloromethane leads to the rapid formation of ring-opened 4-substituted 3-butenyl-l-trifluoroacetate esters 16 (Eq. 20).130 Cyclopropylcarbinyl trifluoroacetates are not formed. Ring opening is facilitated by phenyl substituents. Addition of organosilicon hydrides to the reaction mixture favors the formation of cyclopropylmethanes 17 and suppresses the formation of the ring-opened esters.130... 

Aliphatic ketone, methylene function reduction, 6-phenylhex-l-ene, 131-132 Alkane reduction alcohols, 12-27 allyl alcohols, 24 benzyl alcohols, 18-24 cyclopropylcarbinols, 17-18 metal-complexed alcohols,... 

Table 5. Preparation of Cyclopropylcarbinols and Cyclobutanones Using Lithiated Heteratom Substituted Cyclopropanes... 

These electrophilic conjunctive reagents require donor reactants. The cyclopropyl-carbinols as precursors to cyclobutanones arise by simple addition of organometallics. For example, the cyclobutanone 47 derives by addition of vinyllithium to 44 followed by rearrangement with aqueous fluoroboric acid 92). In some cases, this route to cyclopropylcarbinols is preferred. Addition of 41 to aldehydes or ketones... 

Enolates also serve as suitable reaction partners in a directed aldol condensation (Eq. 52) 88) Dehydration of the aldol 51 to give enone (POCl3, HMPA then C5H5N) followed by reduction [LiAlH(nC4H9) (iC4H9)2] produces a vinylogue of a cyclopropylcarbinol 53. Aqueous fluoroboric acid smoothly rearranges 53 to the... 

A bis-vinylogue of a cyclopropylcarbinol 57 arises by standard transformations (Eq. 59) from the Peterson olefination product 56. Here too, acid induced rearrangement proceeds exclusively to the cyclobutanone and not to larger ring products93). 

The opening of cyclopropylcarbinols to homoallylic bromides constituted the first use of cyclopropyl compounds for the stereocontrolled synthesis of natural products. The cyclopropyl conjunctive reagents enhance the richness of this notion. The stereocontrolled opening of vinylcyclopropanes by a homopentadienyl proton shift provides an approach to trisubstituted olefins and thereby a new strategy. The fungal prohormone methyl trisporate B (224) as summarized in Scheme 15 illustrates this conceptual development97). 

The cyclopropylcarbinol nucleosides 172-177 have also been prepared and tested as antiviral, antitumoral, antibacterial agents and neoplasm inhibitors, Eq.68) [230-232]. 

Primare, sekundare und tertiare Cyclopropylcarbinole, die Substituenten im Cyclopropan-Ring tragen (32), werden unter Gleichgewichtsbedingun-gen stets in der Weise geoffnet, daB das hdher substituierte Homoallyl-... 

Auf der anderen Seite werden Cyclopropylcarbinole der Formel (34) nach Reaktionsbedingungen in die primaren Alkohole (35) oder in die seku dSten Siebenringalkobole (36) iiberfiihrt. Fur beide Reaktionswege werd(. ver-schiedene Mechanismen diskutiert (88). 

A novel gold catalyzed example of three-component addition was recently reported by Shi et al. (Equation 8.44) [106]. Terminal aryl alkynes, alcohols and 2-(arylmethy-lene) cyclopropylcarbinols provided an intermolecular tandem hydroalkoxylation/ Prins-type reaction to form 3-oxabicyclo[3.1.0]hexanes from simple materials and under mild conditions, catalyzed by the system AuClPPh3/AgOTf. The proposed mechanism for this reaction is shown in Scheme 8.19. 

Am cyclohutanol. A 1-L, three-necked, round-bottomed flask equipped with a reflux condenser and a magnetic stirring bar is charged with 600 mL of water, 57.5 mL (ca. 0.68 mol) of concentrated hydrochloric acid, and 57.7 g (0.80 mol) of cyclopropylcarbinol (Note 1). The reaction mixture is stirred and refluxed for 3 hr. Cyclobutanol is only partially soluble in water and soon separates. The reaction mixture is allowed to cool to room temperature and the flask is then immersed in an ice bath. To the cold, stirred mixture is added 24 g (0.6 mol) of sodium hydroxide pellets, followed by 6.7 g (0.08 mol) of sodium bicarbonate to complete the neutralization. The mixture is saturated with sodium chloride and extracted for 30 hr with diethyl ether using a liquid-liquid continuous extraction apparatus. The ethereal extract... 

The checkers obtained cyclopropylcarbinol from the Aldrich Chemical Company, Inc. It can be readily prepared by the reduction of cyclopropane-carboxylic acid with lithium aluminum hydride. ... 

The present procedure offers in good yields a simple and ready preparation of pure cyclobutene from the easily available cyclopropylcarbinol. The product is free of the impurities (e.g., 1,3-butadiene, bicyclobutane, methylenecyclopropane) usually obtained with the various methods so far reported. The procedure described for the synthesis of... 

Asymmetric cyclopropanation of olefins can also be achieved by the Simmons-Smith reaction (231). Reaction of ( )-cinnamyl alcohol and the diiodomethane-diethylzinc mixed reagent in the presence of a small amount of a chiral sulfonamide gives the cyclopropylcarbinol in up to 75% ee (Scheme 97) (232a). ( )-Cinnamyl alcohol can be cyclopro-... 

Olah, Roberts and coworkers observed3 1 temperature-dependent chemical shifts for the C4H7+ ion, prepared from cyclopropylcarbinol-l-l3C. They suggested an equilibration involving nonclassical bicyclobutonium ion 2 and the bisected cyclopropylcarbinyl cation 3 (equation 12). 

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