Preparation and Chemistry

241 [R = C02Alk (Aik = Me, Et, n-Pr, n-Bu)]. In the presence of a trace of acid, compounds 241 ring-contracted to the corresponding compound 242. That these reactions probably involved total degradation of 241 back into urethanes and formaldehyde was demonstrated by the observation that 

Section IV,A,3). Borowski and Haas reported thioamines CF2X-SNH2 (X = F,C1) reacted with formaldehyde to afford, in addition to triazines 242 and 10-membered pentazecine, the tetrazocines 241 (R1 - R4 = SCF3, SCF2C1) (82CB523). 

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Preparation and chemistry of chromium compounds can be found ia several standard reference books and advanced texts (7,11,12,14). Standard reduction potentials for select chromium species are given ia Table 2 whereas Table 3 is a summary of hydrolysis, complex formation, or other equilibrium constants for oxidation states II, III, and VI. 

The use of enamines as protective groups seems largely to be confined to steroid chemistry, where they serve (in their protonated form) to protect the A-B enone system from bromination and reduction. A large body of literature exists on the preparation and chemistry of enamines, which are easily hydrolyzed with water or aqueous acid. 

An excellent review of the preparation and chemistry of sulphoximines (also known as sulphoximides) has been published177. Here, some of the more interesting and important reactions amounting to oxidation at sulphur will be considered. 

The preparation and chemistry of nickel trithiocarbonate complexes have been studied in detail, and both [NKCSs) ] and [Ni(CS4)2 have been isolated (379). Shul man and co-workers (379) reprepared the known [Ni(NH3)3(CS3)]and [Ni(en)3]CS3, and the kinetics of the reaction of Ni(II) with the trithiocarbonate ion in methanol was studied the results confirmed the previously proposed ion-pair mechanism (380). 

Considerable attention has been devoted to the preparation and chemistry of a,/3-unsaturated carbonyl compounds, which are valuable intermediates in organic synthesis [125]. Acid-promoted hydrolysis of alkoxyallenes has therefore frequently been employed to prepare a variety of functionalized a,/8-unsaturated carbonyl compounds [12b, 41, 44, 60, 126]. A recent example is illustrated in Scheme 8.54with C-l-silylated alkoxyallene 218 as a convenient starting material for the synthesis of bicyclo[5.4.0]undec-4-en-2-one 221. Sequential deprotonation and silylation at the terminal C=C bond efficiently transformed 218 into a 1,3-disilylated allene which was converted into the acryloylsilane 219 under acidic conditions. A [3 + 4] annula-tion of intermediate 219 with lithium dienolate 220 furnished bicydic compound 221 in good yield [127]. 

The preparation and chemistry of organic azides have been intensively investigated since about 1960 because of their importance in preparative heterocyclic chemistry and as a source of nitrenes [1]. Many nitrogen-containing heterocycles such as carbazoles, furoxans, azepines, A2-triazolines, triazoles [2], tetrazoles [3], aziridines [4, 5], and azirines have been obtained by either the addition or the decomposition of azides. 

The preparation and chemistry of alkyl and aryl azides [6] and carbamoyl azides [7a, b] have been reviewed [7a]. References to the decomposition and addition of azides have been recently compiled by L Abbe [1]. 

One of the most active areas of research in fluorine chemistry over the last ten years has been the development of the N-F electrophilic fluorinating reagents. These compounds fall into two categories, namely, neutral molecules and salts, and the reader is referred to recent reviews and papers which describe in detail their preparation and chemistry [7,18,197,203-211]. 

Although stable systems of the type 310 are so far unknown, the closely related species 319 (R = Ph, R = Br, Ph) have been isolated as dark-blue crystals. The preparation and chemistry of these species closely... 

Preliminary accounts of the preparation and chemistry of betaines 381 (R = H, Me) have appeared. Compound 381 (R = H) is obtained in high yield by oxidation of dihydronorcoralyne (382 R = H) with w-chloroper-benzoic acid. In a similar manner, ethanolic solutions of dihydrocoralyne (382 R = Me) are oxidized to betaine 381 (R = Me) by air. The study of these compounds has so far been restricted to their oxidation products. Photooxidation of betaine 381 (R = H) followed by borohydride reduction gives a high yield of the phthalideisoquinoline 383. Photooxidation of the 8-methylbetaine 381 (R = Me) gives papaveraldine derivatives (384 R = COMe, CO2Me). The mechanisms of these transformations are open to conjecture. 

The first preparation of a stable benzo[c]furan, l,3-diphenylbenzo[c]furan, was reported in 1905 (05CR(140)1348). The preparation and chemistry of benzo[c]furans has been comprehensively reviewed <78H(9)86s, 80ahc(26)135>. 

The preparation and chemistry of furanones has been comprehensively reviewed (76CRV625,78FOR(35)l33), while synthetic methods for 2(5//)-furanones have been described (75S67). 

Aryl-, as well as heteroaryliodonium salts, belong to the most common, stable, and well investigated class of polyvalent iodine compounds. The preparation and chemistry of aryliodonium salts was extensively covered in several reviews [5,7,9,10]. Diaryliodonium salts have found synthetic application as arylating reagents in reactions with various organic substrates. 

During the past decade, however, significant advances have been made in the preparation and chemistry of aliphatic organopolysilanes. A large number of silicon-silicon compounds of various types (peralkylated, silicon-functional, and carbon-functional) have been prepared, and mechanisms of some of their reactions elucidated. It is hoped that this review will demonstrate how the chemistry of aliphatic organopolysilanes is unique as well as similar to that of organomonosilanes. 

C103F and IO jF were first synthesized in the early 1950s, whereas Br03F was not isolated until 1969 and the detailed chemical behavior of this compound still awaits investigation. The preparation and chemistry of C103F itself was comprehensively reviewed in 1967 (263). 

Only few examples of 1,2,3,5-diazadiphospholes 23 were reported in the literature. The preparation of 1-phenyl-1,2,3,5-diazadiphosphole by the condensation of methylene bis(dichlorophosphine) and a hydrazine in the form of a colorless, air-sensitive liquid is described in CHEC-II(1996) <1996CHEC-II(4)771>. No new research on the preparation and chemistry of 1,2,3,5-diazadiphospholes has been published in the last decade. 

C. The Preparation and Chemistry of the Dimethyl Ether Adduct of Triborane(7)j Diborane(4) Adducts... 

There have been a number of reports on the preparation and chemistry of fused thiazepine derivatives. Toda el al. have noted the stereocontrolled synthesis of tetrahydro-1,5-benzothiazepines, trans- and c/s-263, on reaction of o-aminothiophenol with the epoxide 262 in the presence of magnesium perchlorate the overall yield of 263 was 94% and the trans.cis ratio was 24 76 and the factors controlling the stereochemical outcome were discussed [01H1451 ]. 

The preparation and chemistry of basal-edge-bridged square-pyramidal hexaruthenium complexes has been reviewed.1... 

Some fundamental aspects of polythiophene preparation and chemistry have been investigated. Solution processing of a polythiophene having ester groups has been performed, which after ester cleavage and decarboxylation gave new access to the parent thiophene polymer <07MAC6012>. The mechanism of the photoinduced polymerization of thiophene... 

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