F Allyl alcohol

We subsequently reported that altering the structure of the aryl groups of the tertiary phosphine can indeed produce a more effective catalyst [10]. Thus, replacement of Ph with o-Tol (PF-PPh2 -> PF-P(o-Tol)2) furnishes a ligand that provides improved enantioselectivity and yield for the rhodium-catalyzed isomerization of F-allylic alcohols (Tab. 4.1). 

Selenium dioxide exhibits a useful stereoselectivity in reactions with trisubstituted gem-dimethyl alkenes. The products are always predominantly the /f-allylic alcohol or unsaturated aldehyde221 ... 

Problem 13.50 Suggest a possible industrial preparation for (a) r-butyl alcohol, (f>) allyl alcohol, (c) glycerol (HOCHjCHOHCHjOH). ... 

The second step involves reduction of a propargylic alcohol to an F-allylic alcohol. 

Radical cyclization cf halometkylsilyl ethers (f allylic alcohols 648... 

Stereoselective reduction of acetylenic alcohols to f-allylic alcohols using sodium bis(2-methoxyethoxy)aluminum hydride (SMEAH, also known as Red-Al) or UA1H4-... 

The dioxaborolane-mediated cyclopropanation can also be used in the reagent-controlled cyclopropanation of chiral non-racemic f -allylic alcohols (46) to effectively give aw/f-cyclopropylmethanols (47) (Figure 2). 

Even a fourfold Heck reaction utilizing the tetradiazonium salt with a tetraphenyl-methane framework has been demonstrated with various alkenes to yield the corresponding fourfold coupling prodncts.f" Allyl alcohols did not conple with the tetradiazonium salt, but the tetrakis(p-iodophenyl)methane did yield the tetraaldehyde upon coupling with allyl alcohol (Scheme... 

Pyridinium / -toluenesulfonate, f-BuOH or 2-butanone, reflux, 80-99% yield. This method is useful for allylic alcohols. MEM ethers are also cleaved under these conditions. 

Cyclisation of the allylic alcohols derived from the condensation of 2-ferf.butylthiobenzaldehyde and methylketones provides a new route to substituted 2/f-l-benzothiopyrans <96TL5077>. 

The Asymmetric Cyclopropanantion of Acyclic Allylic Alcohols Efficient Stereocontrol with lodomethylzinc Reagents," Charette. A.B. Marcoux, J.-F. Synlett, 1995, 1197... 

It has also been shown that dimethylsilyl enolates can be activated by diisopropylamine and water and exhibit a high reactivity toward iV-tosyl imines to give Mannich-type reaction products in the absence of a Fewis acid or a Bronsted acid.51 For example, the reaction of [(1-cyclohexen-l-yl)oxy]dimethylsilane with 4-methyl-A -(phenylmethylene)benzene sulfonamide gave re/-4-methyl-N- (f )-[(15)-(2-oxocyclohexyl)phenyl-methyl] benzenesulfonamide (anti-isomer) in 91% yield stereoselectively (99 1 anti syn) (Eq. 11.30). On the other hand, Fi and co-workers reported a ruthenium-catalyzed tandem olefin migration/aldol and Mannich-type reactions by reacting allyl alcohol and imine in protic solvents.52... 

Copper(II) triflate is quite inefficient in promoting cyclopropanation of allyl alcohol, and the use of f-butyl diazoacetate [164/(165+166) = 97/3%] brought no improvement over ethyl diazoacetate (67/6 %)162). If, however, copper(I) triflate was the catalyst, cyclopropanation with ethyl diazoacetate increased to 30% at the expense of O/H insertion (55%). As has already been discussed in Sect. 2.2.1, competitive coordination-type and carbenoid mechanisms may be involved in cyclopropanation with copper catalysts, and the ability of Cu(I) to coordinate efficiently with olefins may enhance this reaction in the intramolecular competition with O/H insertion. 

Model (1) further suggests that, if the substrate is a secondary allylic alcohol (R4 / 11, R5 = H or r4=h, rVh), enantiomeric alcohols are epoxidized at different rates when (R,R)-DAT is used as the chiral auxiliary, (5)-allylic alcohol (R4 f H, R5 = H) suffers less steric hindrance from the tartrate ligand and is oxidized faster than (R)-allylic alcohol (R4 = H, R5 f H).37 As the ester alkyl group of DAT becomes bulkier, the hindrance becomes more intense and the relative... 

Another interesting asymmetric epoxidation technique using metal catalysis involves the vanadium complexes of A-hydroxy-[2.2]paracyclophane-4-carboxylic amides (e.g., 19), which serve as catalysts for the epoxidation of allylic alcohols with f-butyl hydroperoxide as... 

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