摘要:

AbstractNitrogen is one of the best known leaving groups. Decomposition of aliphatic diazonium ions has rendered carbocations (carbon cations) accessible in cases where the solvolysis of halides or sulfonic esters follows different pathways. The limits of unassisted decomposition are seen in primary diazonium ions, where the participation of external nucleophiles and of neighboring groups in the elimination of nitrogen becomes noticeable. Cyclopropanediazonium ions occupy a position intermediate between aliphatic and aromatic diazonium ions. New versatile methods of generating aliphatic diazonium ions facilitate their preparative use.

ISSN:0570-0833    

DOI:10.1002/anie.197602511

出版商:Hüthig&Wepf Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractThe compounds of oxygen,i.e.OH acids, ethers, quinones, aldehydes, ketones, carboxylic esters and amine oxides, sulfoxides, and phosphane oxides, are compared and contrasted with those compounds which contain a C(CN)2moiety in place of the characteristic O atom. In their typical properties the pairs of analogs frequently display surprising agreement. The purpose of such analogy studies lies primarily in the estimation of reactivities; their limits are reached where specific properties of the structual components become effective.

ISSN:0570-0833    

DOI:10.1002/anie.197602611

出版商:Hüthig&Wepf Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractThe oxazoline ring system, first prepared in 1884, has only in the last five years been shown to possess considerable utility in the synthesis of a variety of functionalized organic compounds. By appropriate metalation of the 2‐alkyl substituent it is possible to prepare a variety of homologated carboxylic acid derivatives, both chiral and achiral. Various other manipulations of the oxazoline ring lead to aldehydes, ketones, lactones, amino acids, thiiranes, and olefins. Due to the inertness of the oxazoline ring system to various reagents (RMgX, LiAlH4, CrO3, mild acid or alkali) it may be utilized as a protecting group for carboxylic acids during the transformations involving the above reagents. Two major new developments in oxazoline chemistry involve (a) the use of a chiral oxazoline as a reagent for asymmetric synthesis of chiral carboxylic acids, lactones, alcohol, thiiranes, and olefins and (b) a new mode of aromatic substitution in which the aryloxazolines act as nucleophilic or electrophilic reagents. This behavior has led to a variety of polysubstituted benzenes and biphenyls which would be inaccessible by classical routes. A variety of examples illustrating the utility of oxazolines indicated above are presented so that the reader may appreciate the vast potential of this simple ring system in synthesi

ISSN:0570-0833    

DOI:10.1002/anie.197602701

出版商:Hüthig&Wepf Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractThe reactions of electrochemical splitting may be successfully used for removal of protecting groups. Theoretical and preparative aspects of the method of electro‐deprotection are discussed, and examples of its use are given. The removal often requires high potentials. The use of modified protecting groups (“inner activation”) or of catalysts (electron carriers) which facilitate electron transfer against the standard potential gradient (“external activation”), can greatly increase the scope of the electrochemic

ISSN:0570-0833    

DOI:10.1002/anie.197602811

出版商:Hüthig&Wepf Verlag    

年代:1976

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197602931

出版商:Hüthig&Wepf Verlag    

年代:1976

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197602942

出版商:Hüthig&Wepf Verlag    

年代:1976

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197602951

出版商:Hüthig&Wepf Verlag    

年代:1976

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197602972

出版商:Hüthig&Wepf Verlag    

年代:1976

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197602981

出版商:Hüthig&Wepf Verlag    

年代:1976

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197602991

出版商:Hüthig&Wepf Verlag    

年代:1976

数据来源: WILEY