Propenylation

Glycerol -dichlorohydrin, 2.3-dichloro-propanol, CH2CI CHC1 CH2 0H. Colourless liquid, b.p. 182 C. Prepared by the chlorination of propenyl alcohol. Oxidized by nitric acid to 1,2-dichloropropionic acid. Reacts with NaOH to give epichlorohydrin. 

CH rCHCH NHCSNH. Colourless crystalline solid with a faint garlic-like odour m.p. 74 C. Manufactured by treating propenyl isothiocyanate with a solution of ammonia in alcohol. It has been given by injection in the treatment of conditions associated with the formation of excessive fibrous tissue. Toxic side reactions may occur. Propenyl thiourea is a chemical sensitizer for photographic silver halide emulsions. 

The synthesis of spiro compounds from ketones and methoxyethynyl propenyl ketone exemplifies some regioselectivities of the Michael addition. The electrophilic triple bond is attacked first, next comes the 1-propenyl group. The conjugated keto group is usually least reactive. The ethynyl starting material has been obtained from the addition of the methoxyethynyl anion to the carbonyl group of crotonaldehyde (G. Stork, 1962 B, 1964A). 

In the Sharpless epoxidation of divinylmethanols only one of four possible stereoisomers is selectively formed. In this special case the diastereotopic face selectivity of the Shaipless reagent may result in diastereomeric by-products rather than the enantiomeric one, e.g., for the L -(-(-)-DIPT-catalyzed epoxidation of (E)-a-(l-propenyl)cyclohexaneraethanol to [S(S)-, [R(S)-, [S(R)- and [R(R)-trans]-arate constants is 971 19 6 4 (see above S.L. Schreiber, 1987). This effect may strongly enhance the e.e. in addition to the kinetic resolution effect mentioned above, which finally reduces further the amount of the enantiomer formed. 

Unexpectedly, a completely different reaction took place in the oxidation of 2-(l-propenyl)phenol (111) with PdCh. Carpanone (112) was obtained in one step in 62% crude yield. This remarkable reaction is explained by the formation of o-quinone, followed by the radical coupling of the side-chain. Then the intramolecular cycloaddition takes place to form carpanone[131]. 

With higher alkenes, three kinds of products, namely alkenyl acetates, allylic acetates and dioxygenated products are obtained[142]. The reaction of propylene gives two propenyl acetates (119 and 120) and allyl acetate (121) by the nucleophilic substitution and allylic oxidation. The chemoselective formation of allyl acetate takes place by the gas-phase reaction with the supported Pd(II) and Cu(II) catalyst. Allyl acetate (121) is produced commercially by this method[143]. Methallyl acetate (122) and 2-methylene-1,3-diacetoxypropane (123) are obtained in good yields by the gas-phase oxidation of isobutylene with the supported Pd catalyst[144]. 

The isocoumarin 151 is prepared by the intramolecular reaction of 2-(2-propenyDbenzoic acid (149) with one equivalent of PdCbjMeCN) . However, the (Z)-phthalide 150 is obtained from the same acid with a catalytic amount of PdjOAc) under 1 atm of Oi in DMSO, alone is remarkably efficient in reoxidizing Pd(0) in DMSO. The isocoumarin 151 is obtained by the reaction of 2-(l-propenyl)benzoic acid (152) under the same conditions[4], 2-Vinylbenzoic acid (153) is also converted into the isocoumarin 154, but not to the five-membered lactone) 167,170],... 

The coupling of the enol triflate 703 with the vinylstannane 704[397] has been applied to the synthesis of glycinoeclepin[576]. The introduction of a (Z)-propenyl group in the / -lactam derivative 705 proceeds by use of tri-2-furylphosphine[577]. However, later a smooth reaction to give the propenyl-iactam in 82% yield was achieved simply by treating with Pd(OAc)2 in NMP or CH2CI2 for 3-5 min without addition of LiCI and the phosphine ligand[578]. 

The (l-ethynyl)-2-propenyl acetate derivative 111 undergoes an interesting PdCl2(PhCN)2-catalyzed cyclization to form the 2-cyclopentenone 112[47], A Pd-carbene complex is assumed to be an intermediate of the formation of 112. 

When benzaldehyde or its substituted derivatives are added to carbon disulfide and a-aminonitrile, the corresponding 2-mercapto-5-(p-R-benzylideneamino)thiazoles (215), R = hydrogen atom or a propenyl or phenyl group and Ar = aryl, are obtained (Scheme 112) (393, 442, 694). Yields ranged from 40 to 60% (Table II-34b). 

Pentanedioyl, see Glu-taryl CH2—CH2— pynyl Propenoyl, see Acryloyl 1-Propenyl CH3—CH=CH—... 

Pentanoyl, see Valeryl Pentenyl (2- shown) CH3—CH2—CH=CH— 2-Propenyl, see Allyl Propenylene —CH2—CH=CH—... 

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