Addition Prins

Uses Emulsifier for agric. toxicants, ind. chlorinated insecticides and herbicidal esters primary emulsifier in emulsion polymerization of acrylic monomers, vinyl acetates, and vinyl acrylics textile antistet and lubricant cosmetics additive prin-cipai detergent in industrial alkaline deanersfor bottles, laundry, dairy, aircrafL metai, steam, or electrolytic deaning paint and stripping agent solvent cleaner Properties Yel. d. liq. disp. in water sp.gr. 1.05-1.06 acid no. 100-120 (pH 5.5) ... 

Condensation of vinyl chloride with formaldehyde and HCl (Prins reaction) yields 3,3-dichloro-l-propanol [83682-72-8] and 2,3-dichloro-l-propanol [616-23-9]. The 1,1-addition of chloroform [67-66-3] as well as the addition of other polyhalogen compounds to vinyl chloride are cataly2ed by transition-metal complexes (58). In the presence of iron pentacarbonyl [13463-40-6] both bromoform [75-25-2] CHBr, and iodoform [75-47-8] CHl, add to vinyl chloride (59,60). Other useful products of vinyl chloride addition reactions include 2,2-di luoro-4-chloro-l,3-dioxolane [162970-83-4] (61), 2-chloro-l-propanol [78-89-7] (62), 2-chloropropionaldehyde [683-50-1] (63), 4-nitrophenyl-p,p-dichloroethyl ketone [31689-13-1] (64), and p,p-dichloroethyl phenyl sulfone [3123-10-2] (65). 

Formaldehyde also reacts with butadiene via the Prins reaction to produce pentenediols or their derivatives. This reaction is cataly2ed by a copper-containing catalyst in a carboxyUc acid solution (57) or RuCl (58). The addition of hydrogen also proceeds via 1,2- and 1,4-addition. 

The acid-catalyzed addition of an aldehyde—often formaldehyde 1—to a carbon-carbon double bond can lead to formation of a variety of products. Depending on substrate structure and reaction conditions, a 1,3-diol 3, allylic alcohol 4 or a 1,3-dioxane 5 may be formed. This so-called Prins reaction often leads to a mixture of products. 

The Prins reaction often yields stereospecifically the and-addition product this observation is not rationalized by the above mechanism. Investigations of the sulfuric acid-catalyzed reaction of cyclohexene 8 with formaldehyde in acetic acid as solvent suggest that the carbenium ion species 7 is stabilized by a neighboring-group effect as shown in 9. The further reaction then proceeds from the face opposite to the coordinating OH-group " ... 

The addition of an alkene to formaldehyde in the presence of an acid catalyst is called the Prins reaction.Three main products are possible which one predominates depends on the alkene and the conditions. When the product is the 1,3-diol or the dioxane, the reaction involves addition to the C=C as well as to the C=0. The mechanism is one of electrophilic attack on both double bonds. The acid first protonates the C=0, and the resulting carbocation attacks the C=C ... 

Ene and Carbonyl-Ene Reactions. Certain double bonds undergo electrophilic addition reactions with alkenes in which an allylic hydrogen is transferred to the reactant. This process is called the ene reaction and the electrophile is known as an enophile A When a carbonyl group serves as the enophile, the reaction is called a carbonyl-ene reaction and leads to [3,-y-unsalurated alcohols. The reaction is also called the Prins reaction. 

Protonic acid and Lewis acids can activate carbonyls to facilitate the addition of nucleophile attacks in aqueous media. The Prins reaction, reaction with alkyne, and Friedel-Crafts-type reactions have been discussed in related chapters in detail. 

Scheme 2.56. Aldol/Prins-type/addition sequence.

Quite recently, a domino Diels-Alder/Prins/pinacol reaction was reported by Barriaulfs group [38]. This novel method is very reliable and efficient for the synthesis of highly functionalized bicyclo[m.n.l]alkanones. In addition, Aube and coworker [39] used a combination of a Diels-Alder and a Schmidt reaction within the total synthesis of the Stemona alkaloid stenine [40]. 

There are though a number of other reasons for believing that the results of Prins et al. do correspond to those for the Fe(Cp)2+ system. Thus, it is hard to understand the wide range of g values found for the various substituted ferricenium complexes if these are all to be ascribed to Fe3+, and in addition the distortion parameters deduced by Prins et al. are very much of the same order of magnitude as those determined for the carborane and... 

Conversion of the A-ring aldehyde 50 to hydroxyallylsilane 57 is accomplished in a three-step sequence involving addition of allylstannane 49 followed by oxidation-reduction for diastereomeric enrichment at Cll. With both hydroxyallylsilane 57 and aldehyde 51 in hand, intermolecular Prins pyran annulation proceeds smoothly to furnish the tricyclic compound 58 in 61 % isolated yield. 

Yamaguchi esterification of A-ring fragment 59 and C-ring fragment 60 delivers compound 65, the substrate for silyl-Prins macrocyclization, a transformation that proceeds in 65 % isolated yield under remarkably mild conditions. Notably, after the point of convergence, only five additional steps are required to access bryostatin 9 (Scheme 5.7). 

Processes that enable direct catalytic C-C functionalization of carbinol C-H bonds are highly uncommon. Rh-catalyzed alcohol-vinylarene C-C coupling has been described. The requirement of BF3 and trends in substrate scope suggest these processes involve alcohol dehydrogenation-reductive Prins addition [26-29]. 

During the coverage period of this chapter, reviews have appeared on the following topics reactions of electrophiles with polyfluorinated alkenes, the mechanisms of intramolecular hydroacylation and hydrosilylation, Prins reaction (reviewed and redefined), synthesis of esters of /3-amino acids by Michael addition of amines and metal amides to esters of a,/3-unsaturated carboxylic acids," the 1,4-addition of benzotriazole-stabilized carbanions to Michael acceptors, control of asymmetry in Michael additions via the use of nucleophiles bearing chiral centres, a-unsaturated systems with the chirality at the y-position, and the presence of chiral ligands or other chiral mediators, syntheses of carbo- and hetero-cyclic compounds via Michael addition of enolates and activated phenols, respectively, to o ,jS-unsaturated nitriles, and transition metal catalysis of the Michael addition of 1,3-dicarbonyl compounds. ... 

A representative example for the information extracted from a TRMC experiment is the work of Prins et al. [141] on the electron and hole dynamics on isolated chains of solution-processable poly(thienylenevinylene) (PTV) derivatives in dilute solution. The mobility of both electrons and holes as well as the kinetics of their bimolecular recombination have been monitored by a 34-GHz microwave field. It was found that at room temperature both electrons and holes have high intrachain mobilities of fi = 0.23 0.04 cm A s and = 0.38 0.02 cm / V s V The electrons become trapped at defects or impurities within 4 ps while no trapping was observed for holes. The essential results are (1) that the trap-free mobilities of electrons and holes are comparable and (2) that the intra-chain hole mobility in PTV is about three orders of magnitude larger than the macroscopic hole mobility measured in PTV devices [142]. This proves that the mobilities inferred from ToF and FET experiments are limited by inter-chain hopping, in addition to possible trapping events. It also confirms the notion that there is no reason why electron and hole mobilities should be principally different. The fact... 

Other nucleophilic additions conducted in aqueous media can be found in the literature (Lubineau et al., 1994 Strauss, 1999). These reactions will include the benzoin condensation, the Prins reaction, and the Wittig-Horner reaction, and the Baeyer-Villi-ger oxidation. 

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. 

In addition to his excellence in research and his inspired teaching, Willem Prins was known for the breadth of his intellectual interests and for his active involvement in the concerns of colleagues and students. 

The stereochemistry of the Prins reaction is complex. In the transformation of cyclohexene and 2-butenes anti stereoselective addition was observed,67-69 whereas syn addition of two formaldehyde units takes place in the formation of 1,3-dioxanes from substituted styrenes.70 Most of the transformations are, however, nonstereo-selective,71 72 accounted for by carbocation 18. 

Prins reaction (cf 10, 186-187). Dimethylaluminum chloride is an effective catalyst for the ene addition of formaldehyde (as trioxane or paraformaldehyde) to mono- and 1,2-disubstituted alkenes.5 When 1.5-2.0 equiv. of the Lewis acid is used, homoallylic alcohols are obtained, usually in high yield. y-Chloro alcohols, formed by cis-addition of -Cl and -CH2OH to the double bond, are sometimes also observed when only 1 equiv. of the Lewis acid is present. The advantage of this reaction over the Prins reaction (using HC1) is that m-dioxanes are not formed as by-products, because formaldehyde no longer functions as a nucleophile when complexed to the Lewis acid. 

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