An Improved Synthesis of 4-Cycloheptenone

A previous paper² described the chemistry of 1-aza-4-cyclo-octene 1 which we prepared from 4-cycloheptenone 2 according to the method of Bahurel et al.³ This procedure involves the condensation of cis-1,4-dichloro-2-butene with ethyl sodio-acetoacetate, yielding, a mixture of four isomers 3–6. The entire mixture is then heated with aqueous potassium hydroxide under reflux for four hours. Under these conditions 5 undergoes decarbethoxylation to yield 4-acetylcyclopentene 7, while 3 yields 2, presumatly by Cope rearrangement atid decarbethoxylation (2 is present in almost negligiblequantity but was reported³ to also yield 2).     

Expedient Preparation of a Highly Functionalized Diquinane Building Block

A high yield four-step synthesis of the useful α-enoni ketal is described.     

The Nitro Ketal Approach to Furane Systems. Total Synthesis of Racehic Bilobanone

Continuing our studies with the chemistry of ketals of β-nitro ketones¹, we wish to describe a new furane synthesis exemplified by a total synthesis of the sesquiterpene bilobanone 1 ².     

The Structure of o-Hydroxyaryloxy-bis-(o-arylenedioxy)-phosphoranes and their Acid-Base Properties

Abstract

The crystalline phosphoranes have been obtained. IR-, UV- and NMR spectra of phosphoranes (Ia,b) and their interaction products with nitrogen bases have been investigated. It was determined that phosphoranes have structure (I) with pentacoordinate phosphorus and phenolic hydroxy group, while their products of interactions with nitrogen bases have the ionic structure (II) with hexacoordinate phosphorus (II). The X-ray difraction approves the structure (I) for phosphorane Ib.     

The Reaction of (Phenyldimethylsilyl)dichloromethyllithium with Organoboranes. A Synthesis of α-Hydroxyorganosilanes and Ketones

The α-transfer reaction of organoboranes has been utilized to great advantage in the employment of organoboranes in synthesis.² We report here that this process can be used as illustrated in eq 1 to generate α-hydroxyorganosilanes, which can be converted to ketones. This procedure serves to incorporate two of the groups of the organoborane into the product as well as generating the hydroxyl group via oxidation of the newly formed carbon-boron bond.     

Symmetrical Ketones from Aldehyde Trimethylsilyl Enol Ethers on Storage: A Cautionary Note

The widespread use of trialkylsilyl enol ethers has dramatically increased the utility of enolate anion chemistry.¹ These enol ethers are readily prepared, reactive, and in many instances are stable enough to be commercially available. We have been using trimethylsilyl enol ethers as aldehyde enolate precursors and wish to report some observations regarding storage of these 1-alkyl-2-trimethylsilyloxyethenes. We have noted that after 2–3 months in sealed glass ampuoles these trimethylsilyl enol ethers contained significant amounts of symmetrical ketones.     

Novel synthesis of graveoline and graveolinine

Cyclization of 2-aryl amides with base lead to quinolone derivatives. Both graveoline and graveolinine were synthesized.GRAPHICAL ABSTRACT