3.3- dimethyl-allyl alcohol

The use of dimethyl sulfoxide-acetic anhydride as a reagent for the oxidation of unhindered steroidal alcohols does not appear to be as promising due to extensive formation of by-products. However, the reagent is sufficiently reactive to oxidize the hindered 11 j -hydroxyl group to the 11-ketone in moderate yield. The use of sulfur trioxide-pyridine complex in dimethyl sulfoxide has also been reported. The results parallel those using DCC-DMSO but reaction times are much shorter and the work-up is more facile since the separation of dicyclohexylurea is not necessary. Allylic alcohols can be oxidized by this procedure without significant side reactions. 

Benzaldehyde dimethyl acetal 121 reacts, for example, with the silylated allylic alcohol 645, in the presence of SnCl2-MeCOCl, via an intermediate analogous to 641, to the 3-methylenetetrahydrofuran 646 and methoxytrimethylsilane 13 a [182], whereas benzaldehyde dimethyl acetal 121 reacts with the silylated homoallylalco-hol 640 in the presence of TMSOTf 20 to afford exclusively the ds 4-vinyltetrahy-drofuran 647 and 13 a [183]. A related cyclization of an a-acetoxy urethane 648 containing an allyltrimethylsilane moiety gives the 3-vinylpyrrohdine 649 in 88% yield and trimethylsilyl acetate 142 [184, 185]. Likewise, methyl 2-formylamido-2-trimethylsilyloxypropionate reacts with allyltrimethylsilane 82 or other allyltri-methylsilanes to give methyl 2-formamido-2-aUyl-propionate and some d -unsatu-rated amino acid esters and HMDSO 7 [186] (Scheme 5.56). 

A. Claisen Rerrangements of Ketene Aminats and Imidates. A reaction that is related to the orthoester Claisen rearrangement utilizes an amide acetal, such as dimethylacetamide dimethyl acetal, in the exchange reaction with allylic alcohols.257 The products are y, 8-unsaturated amides. The stereochemistry of the reaction is analogous to the other variants of the Claisen rearrangement.258... 

Selenium dioxide reveals a useful stereoselectivity when applied to trisubstituted gem-dimethyl alkenes. The products are predominantly the Zs-allylic alcohol or... 

ETHYLENE GLYCOL ETHYL MERCAPTAN DIMETHYL SULPHIDE ETHYL AMINE DIMETHYL AMIDE MONOETHANOLAMINE ETHYLENEDIAMINE ACRYLONITRILE PROPADIENE METHYL ACETYLENE ACROLEIN ACRYLIC ACID VINYL FORMATE ALLYL CHLORIDE 1 2 3-TRICHLOROPROPANE PROPIONITRILE CYCLOPROPANE PROPYLENE 1 2-DICHLOROPROPANE ACETONE ALLYL ALCOHOL PROPIONALDEHYDE PROPYLENE OXIDE VINYL METHYL ETHER PROPIONIC ACID ETHYL FORMATE METHYL ACETATE PROPYL CHLORIDE ISOPROPYL CHLORIDE PROPANE... 

Using methods developed by Sharpless (68), Reich (69), and others, the optically active 4,4-dimethyl-2-cyclohexenol is prepared in excellent yield from the corresponding chiral selenide (eq. [19]). The (S)-4,4-dimethyl-3-p-methylphenylselenocyclohexanone, [a] 42.1° (e.e. 39%), was reduced with sodium borohydride to the (one) diastereomeric alcohol, [a] 11.0°, in quantitative yield and converted to the allylic alcohol, [a] — 17.7°, with an e.e. of 40%. 

Sattelkau and Eilbracht90 have exploited the Claisen rearrangement of allyl vinyl ethers in their synthesis of several spiro compounds. As shown below in equation 62, 7,9-dimethyl-l,4-dioxa-spiro[4,5]decan-8-one, 118, was converted to a ,/J-unsaturated ester 119 which was reduced to allyl alcohol 120906. Allyl vinyl ether 121 underwent a rhodium-catalyzed Claisen rearrangement to afford 7r,13r-dimethyl-l,4-dioxa-(8rC9)-dispiro[4.2.4.2]tetradecan-10-one (122) in 36% yield. 

ASYMMETRIC HYDROGENATION OF ALLYLIC ALCOHOLS USING BINAP-RUTHENIUM COMPLEXES (S)-(-)-CITRONELLOL (6-Octen-1-ol, 3,7-dimethyl, (S)-)... 

The chemistry and procedures for modification of the - CO2H groups of PAA hyperbranched grafts on PE powder were analogous to those used for PAA grafts on PE or PP films and wafers. For example, a 90% yield in ester formation was possible using acid-catalyzed Fisher esterification. Likewise, quantitative reduction (ethyl chloroformate activation, borane-dimethyl sulfide reduction) to hyperbranched poly(allyl alcohol)s and amidation all could be carried out using procedures like those used for PAA/Au surfaces. 

Regioselective [4-1-2] cycloadditions to Cjq are also possible with 2,3-dimethyl-buta-1,3-diene (4) and with the monoterpene 7-methyl-3-methylideneocta-l,6-diene (5, myrcene) [22]. These monoadduct formations proceed under mild and controlled conditions. Most of these addition products of 1,3-butadiene derivatives (e.g. 4, 5, 8-12) are unstable against air and light [25]. The dihydrofuUerene moiety in the Diels-Alder adducts act as a 02-sensitizer and promotes the oxidation of the cyclohexene moiety to the hydroperoxide. Reduction of the hydroperoxide with PPhj yields the corresponding allylic alcohols [25]. 

Alkynylepoxy alcohols of high enantiomeric purity, obtained via Sharpless oxidation of allylic alcohols (see Section D.4.5) react smoothly with excess dialkylcuprate/magnesium bromide to give (/Vf.25)-3.4-alkadiene-1.2-diols in reasonable overall yield and with high anti selectivity when performed at low temperature and by using the dimethyl sulfide complex of copper(I) bromide to synthesize the cuprates42. 

In their stereorational synthesis of (+)-[10.10] 61b, they reacted the epoxide 107 with a 1 1 3-butenylmagnesium bromide-cuprous iodide complex in dimethyl-sulfide-THF at low temperature. The predominant SN2 pathway gave the (+)-( )-allyl alcohol 108 whose Sharpless asymmetric epoxidation in dichloromethane at —23 °C for 10 min provided the corresponding epoxy alcohol and recovered (+)-(R)-allyl alcohol 108 (78 % yield and 95 % optical purity). The (R)-configuration was assigned following the Sharpless model61 for allylic alcohol epoxidation. 

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