3- Methyl-1-butene synthesis

A C5 synthetic unit which has ylide functionality and which is likewise accessible from 2-hydroxy-2-methyl-but-3-enal-dimethylacetal (27) has proved suitable particularly for the synthesis of apocarotenals. The copper-catalyzed reaction of (27) with triphenylphosphine (15) in the presence of aqueous acid leads to 4-triphenyl-phosphonium-2-methyl-buten-2-al (33). The bifunctional C5 ylenal (34), which is important for carotenoid syntheses, is formed therefrom with proton acceptors. 

P12.1 Calculate the equilibrium composition of the TAME (tertiary amyl methyl ether) synthesis in the liquid phase using equimolar amounts of methanol (MeOH) and 2-methyl-2-butene (2M2B) at 25 C and 80 C... 

The isoprenoid compound shown is a scent marker present in the urine of the red fox Sug gest a reasonable synthesis for this substance from 3 methyl 3 buten 1 ol and any necessary organic or inorganic reagents... 

The synthesis of isotactic polymers of higher a-olefins was discovered in 1955, simultaneously with the synthesis of isotactic PP (1,2) syndiotactic polymers of higher a-olefins were first prepared in 1990 (3,4). The first commercial production of isotactic poly(l-butene) [9003-29-6] (PB) and poly(4-methyl-l-pentene) [9016-80-2] (PMP) started in 1965 (5). 

An example of a specialty olefin from an amyl alcohol is Phillips Petroleum s new process for 3-methyl-1-butene (used in the synthesis of pyrethroids) from the catalytic dehydration of 3-methyl-1-butanol (21,22). The process affords 94% product selectivity and 94% alcohol conversion at 310°C and 276 kPa (40 psig). 

A mixture of sodamide, bromoanisole, and l-methoxy-2-methyl-l-(trimethylsilyl-oxy)-l-butene were reacted at room temperature at a 50 millimolar scale. After some two horns, with slight emission of ammonia, the reaction suddenly became exothermic, with violent gas emission and on one occasion a fire. This was a modest scale-up of a literature procedure for synthesis of 2-alky lbenzoic acids, via a benzyne intermediate. It is advised that this reaction be employed only on smaller scale, with safety precautions. The reaction must pass through a benzocyclobutane intermediate, this, or another, high energy species might accumulate and then decompose. 

Somei adapted this chemistry to syntheses of (+)-norchanoclavine-I, ( )-chanoclavine-I, ( )-isochanoclavine-I, ( )-agroclavine, and related indoles [243-245, 248]. Extension of this Heck reaction to 7-iodoindoline and 2-methyl-3-buten-2-ol led to a synthesis of the alkaloid annonidine A [247]. In contrast to the uneventful Heck chemistry of allylic alcohols with 4-haloindoles, reaction of thallated indole 186 with 2-methyl-4-trimethylsilyl-3-butyn-2-ol affords an unusual l-oxa-2-sila-3-cyclopentene indole product [249]. Hegedus was also an early pioneer in exploring Heck reactions of haloindoles [250-252], Thus, reaction of 4-bromo-l-(4-toluenesulfonyl)indole (11) under Heck conditions affords 4-substituted indoles 222 [250], Murakami described the same reaction with ethyl acrylate [83], and 2-iodo-5-(and 7-) azaindoles undergo a Heck reaction with methyl acrylate [19]. 

Hegedus synthesis of ( )-clavicipitic acid //-acetyl methyl ester culminated in the Pd-induced cyclization of 238 to 239, the latter of which was reduced to the target mixture [251], Substrate 238 was prepared via a Heck reaction with the corresponding 4-bromo compound 223 and 2-methyl-3-buten-2-ol (83%). The cyclization also occurs with tosic acid (97%). 

Mixed C4 olefins (primarily iC4) are isolated from a mixed C olefin and paraffin stream. Two different liquid adsorption high-purity C olefin processes exist the C4 Olex process for producing isobutylene (iCf ) and the Sorbutene process for producing butene-1. Isobutylene has been used in alcohol synthesis and the production of methyl tert-butyl ether (MTBE) and isooctane, both of which improve octane of gasoHne. Commercial 1-butene is used in the manufacture of both hnear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE)., polypropylene, polybutene, butylene oxide and the C4 solvents secondary butyl alcohol (SBA) and methyl ethyl ketone (MEK). While the C4 Olex process has been commercially demonstrated, the Sorbutene process has only been demonstrated on a pilot scale. 

Ir-catalyzed alkylation with a nitro compound was applied in a synthesis of flS,2R)-tra s-2-phenylcyclopentanamine, a compound with antidepressant activity (Scheme 9.41) [45]. The reaction of cinnamyl methyl carbonate with 4-nitro-l-butene gave the substitution product with 93% ee in 82% yield. A Grubbs I catalyst sufficed for the subsequent RCM. Further epimerization with NEts yielded a trans-cyclopentene in 83% yield via the two steps, while additional reduction steps proceeded in 90% yield. 

Industrial synthesis of nerolidol starts with linalool, which is converted into ger-anylacetone by using diketene, ethyl acetoacetate, or isopropenyl methyl ether, analogous to the synthesis of 6-methyl-5-hepten-2-one from 2-methyl-3-buten-2-ol. Addition of acetylene and partial hydrogenation of the resultant dehydroner-olidol produces a mixture of cis- and trans-nerolidol racemates. 

Synthesis from Isobutene and Formaldehyde. 3-Methyl-3-buten-l-ol, obtained from isobutene and formaldehyde [43], isomerizes to form 3-methyl-2-buten-... 

Cyclocondensation of 3-methyl-3-buten-l-ol with 3-methylbutanal on silica gel and alumina in the absence of solvents is proposed for synthesis [191]. 

SCHEME 70. Iterative one-pot homologation of terpenoids containing 1,5-diene units with ( )-and (Z)-l,4-diiodo-2-methyl-l-butenes and its application to the synthesis of coenzyme Qs, famesol, and geranylgeraniols171... 

Methyl- 1,3-cyclopentanedione is a key intermediate for the total synthesis of steroids.2 A number of methods have been described for its preparation, among them the condensation of succinic acid with propionyl chloride,3 and that of succinic anhydride with 2-buten-2-ol acetate,4 both in the presence of aluminum chloride. It has also been obtained from 3-methylcyclopentane-1,2,4-trione by catalytic hydrogenation5 and Wolff-Kishner reduction 6 The base-promoted cyclization of 4-oxohexanoic acid ethyl ester and diethyl propionylsuccinate with tertiary alkoxides was first reported by Bucourt.7 The present cyclization process provides an experimentally simple route to 2-methyl-1,3-cyclopentanedione. Using the same procedure, 4-oxoheptanoic acid ethyl ester has been cyclized to give 2-ethyl-l,3-cyclopentanedione in 46% yield... 

Tanaka et al. reported a synthesis of vitamin A derivatives from C15 phosphonates [85]. Vitamin A acetate was prepared in 92% yield by reaction of the C15 phosphonate with 2-methyl-4-acetoxy-2-butenal, Fig. (47). 

In this synthesis the geometry of the acyclic double bonds is controlled through their formation as part of the thiane ring. Thiacyclohexanone (711) was converted to 4-thia-l-methylcyclohexene by reaction with methylmagnesium iodide and subsequent dehydration. Metallation of (712) with s-butyllithium and alkylation of the anion with the epoxide (713) gave a tertiary alcohol which was dehydrated to yield (714). A second alkylation of (714) with trails-4-chloro-3-methyl-2-butene 1-oxide (715) completed the carbon skeleton of the Cis juvenile hormone. Reduction of (716) with lithium in ethylamine and then desulfurization with Raney nickel led to trienol (717), a product converted previously to (718). 

A total synthesis of ( )-aromatin has utilized the lithium anion of the dithiane of (E)-2-methyl-2-butenal as a functional equivalent of the thermodynamic enolate of methyl ethyl ketone in an aprotic Michael addition (Scheme 189) (81JOC825). Reaction of the lithium anion (805) with 2-methyl-2-cyclopentenone followed by alkylation of the ketone enolate as its copper salt with allyl bromide delivered (807). Ozonolysis afforded a tricarbonyl which cyclized with alkali to the aldol product (808). Additional steps utilizing conventional chemistry converted (808) into ( )-aromatin (809). 

This paper concerns the cationic isomerization polymerization of 3-methyl-1-butene and 4-methyl-1-pentene. Specifically, the microarchitecture (composition) of poly(3-methyl-l-butene) and poly(4-methyl-1-pentene) has been investigated, and the effect of synthesis conditions on polymer composition, polymer molecular weight and polymerization rate of 4-methyl-1-pentene has been studied. 

Kennedy and Thomas (1) first reported the synthesis of a crystalline poly(3-methyl- 1-butene) by cationic polymerization at —130°C. Preliminary HNMR studies indicated that the polymer was not simply a tactic modification of the conventional 1,2-polymer but, in fact, possessed a repeat structure which resulted... 

The 300 MHz H NMR and 20 MHz 13C NMR spectra of poly(4-methyl-l-pentene) have been found to be more complex than the corresponding spectra of poly(3-methyl-l-butene) due to the presence of an additional isomer structure in the polymer. Investigation of the 20 MHz 13C NMR spectrum of the polymer has indicated that placement of units in different triad sequences is die cause of multiple methyl proton resonances which have been observed in the H NMR spectra of poly(3-methyl-l-butene) and poly(4-methyl-l-pentene). The use of a computer program for simulating and plotting spectra has enabled measurements of polymer composition to be made of poly(4-methyl-l-pentene) s prepared under a variety of synthesis conditions. 

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