Peterson alkenylation reaction

A double Peterson alkenylation reaction has been successfully conducted using two equivalents of the lithium anion of trimethylsilylacetonitrile, generated with n-BuLi, and the 5,5-dithianeno-nanedial shown in equation eq 15, affording the corresponding (Z,Z)-o, )3-unsaturated dinitrile isomer in 73% yield. The residual material was assigned to the (.Zff)-stereoisomer. ... 

Peterson Alkenylation. The Peterson alkenylation reaction continues to be the major use of trimethylsilylmethyllithium (1) and converts a carbonyl group to a methylene (eq 1). Some enan-tioselectivity has been seen for the addition of 1 to benzaldehyde in the presence of chiral ligands. The ketone substrates can contain functional groups that are con5)atible with the basic conditions. The use of cerium(III) chloride to promote nucleophilic addition of 1 to an enolizable carbonyl compound has continued to prove advantageous. ... 

Aza-1,3-dienes. The reaction of imines (1) of aldehydes obtained from bis(trimethylsilyl)methylamine with aldehydes catalyzed by Bu4NF (Peterson alkenylation) provides 2-aza-l,3-dienes in 65-78% yield. 

Three other groups reported alternative methods for the synthesis of 3-alkenyl-substituted P-lactams. Durst [71] prepared these compounds via a Peterson olefination reaction. Thus, for example, treatment of 3-trimethylsilyl-azetidinone 116 with lithium diisopropyl amide followed by addition of pro-pionaldehyde gave a mixture of 117 and 118 in 66% yield. Tanaka [72] converted allylic stannanes 119 to bromides 120 which were smoothly cyclized to P-lactams 121 in good yield. Ley [73] treated 7i-allyltricarbonyliron complexes with benzylamine in the presence of Lewis acids to afford the corresponding lactam complexes. Oxidation with cerric ammonium nitrate served to liberate the desired P-lactams (Scheme 14). 

This reaction was first reported by Peterson in 1968. It is a two-step synthesis of olefin involving the addition of an a-silyl carbanion to a carbonyl compound to form y3-silyl alcohol (or /3-hydroxy silane) and the elimination of silol. Therefore, this reaction is generally known as the Peterson olefination. In addition, this reaction is also referred to as the Peterson reaction " and Peterson elimination. Occasionally, the Peterson olefination is also called the Peterson alkenation or Peterson alkenylation. ... 

The fluoride ion induced Peterson-type reaction is most widely and effectively utilized in the synthesis of enamines from N-bis(trimethylsilyl)raethylamide derivatives such as 159 [285]. It has been especially exploited to prepare N-1-alkenyl phthalimides and N-l-alkenyl amides 160 (Scheme 2.102) [286-288]. 

R R = aryl, alkyl, alkenyl, CN, SPh, S02Ph, (Et0)2P(0), Ph2P(0) Scheme 2.160. Synthesis of sulfines by a Peterson-type reaction. 

Nucleophilic substitution of a,/3-epoxysilanes followed by the Peterson elimination is valuable for the stereoselective synthesis of alkenes.3 The reactions with lithium phenylsulfide and diphenylphosphide form alkenyl sulfides and alkenylphosphines, respectively, in a stereospecific manner. 7-Metallo-a,/ -epoxysilanes are isomerized to a-siloxyallylmetals by anionic ring opening and subsequent Brook rearrangement (Equation... 

Although the adducts (95) and (96) can be dehydrated under a variety of conditions to provide the corresponding alkenes, the alternative application of the Peterson (Scheme 38) or the Wittig and Hor-ner-Emmons " (Schemes 39-41) reactions to the preparation of alkenyl heterocycles may often be preferred because of the mildness of the reaction conditions required. For example, such an alkenation... 

Additionally, in the elaboration of lactone 35 into key intermediate 11, mild conditions were employed to preserve the sensitive Z alkenyl iodide unit. The completion of synthesis from coupling product 11 was focused on the elaboration of the enyne side chain as well as the introduction of the chloride functionality. These transformations proceeded extremely well with an exception that the Peterson-type olefmation reaction provided only modest geometric selectivity ZIE = 6 1). 

In an analogue of the Peterson reaction, lithiated 2-(trimethylsilyl-methyl)pyridine (26) reacts with -aromatic aldimines to give -2-alkenyl-pyridines in high yield and with high stereoselectivity (greater than 99.5% E-configuration). Ketimines and aliphatic imines give much lower yields. ... 

Silyl(methoxy)benzotriazol-l-ylmethane 62 is lithiated with BuLi to give the corresponding anion, which undergoes Peterson reactions with carbonyl compounds (Scheme 2.40) [100, 101]. The products, l-(l-methoxy-l-alkenyl)benzotriazoles 63, are synthetically equivalent to an acylbenzotriazole synthon in which the carbonyl group is masked as an enol ether [102, 103]. Transformation of the alkenyl ethers into carboxyhc acids is readily achieved by treatment with zinc bromide and hydrochloric add in refluxing 1,4-dioxane [104]. 

The Peterson reactions of a-sUylbenzyl carbamates provide a method for the preparation of aromatic alkenyl carbamates. Addition of carbonyl compounds to the carbanions derived from the a-sUylbenzyl carbamates 64 with Bu Li leads directly to the corresponding alkenyl carbamates 65 with Z-selectivity (Scheme 2.41)... 

Scheme 2.41. Synthesis of alkenyl carbamates by the Peterson reaction.

Scheme 2.43. Synthesis of 1-alkenyl sulfides by the Peterson reaction.

H. Me, Ph R = alkyl, alkenyl, atyl, heletoatyl Scheme 2.56. Synthesis of a, -unsaturated sulfonamides by the Peterson reaction. 

The carbanions of (trimethylsilylmethyl)iminophosphoranes 108 undergo Peterson reactions with aldehydes to give (l-alkenyl)iminophosphoranes 109 rather than aza-Wittig reactions (Scheme 2.65) [171]. The reactions usually afford a mixture of the E- and Z-isomers of 109, with the -products predominating. These carbanions undergo similar reactions with ketones. 

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