ChemInform Abstract: STEREOCHEMISTRY OF THE REDUCTION OF 7‐CHLORO‐SUBSTITUTED 2‐BICYCLO(4.1.0)HEPTANONES

Abstract

Durch Reaktion der Cyclohexenole (I) mit Dichlorcarben werden die durch Kristallisation trennbaren Bicycloheptanole (II) bzw. (III) erhalten und zu den Bicycloheptanonen (IV) oxidiert.

Synthesis of β-, γ-, δ-, ..., ω-Halogenated Ketones and Aldehydes

“…180 Analogously, treatment of an alcohol with Na 2 Cr 2 O 7 or K 2 Cr 2 O 7 in the presence of H 2 SO 4 has been reported in the synthesis of halogenated cyclopropyl ketones 181 and chlorinated bicyclo[4.1.0]heptan-2-ones (Scheme 116). 182 This procedure is compatible with water-immiscible solvents such as Et 2 O and benzene. 183 Pyridinium Chlorochromate (PCC).…”

The resolution of trans-2,2-dichloro-3-methylcyclopropanecarboxylic acid via crystallization of its salts with (+)- and (−)-α-phenylethylamine, and the transformation of the resulting enantiomers into (R)- and (S)-dimethyl 2-methylsuccinates

“…The development of a convenient procedure for the preparation of acid trans-1 in enantiomerically pure form could provide a new pathway to chiral bifunctional compounds with isopentane carbon chain, because the esters and N,N-dialkyl amides of the a-unsubstituted dichlorocyclopropanecarboxylic acids could be involved in the nucleophilic substitution of the halogen atoms and subsequent cleavage of the activated cyclopropane ring. 5 Enantiomerically pure acids 1 could also be used as sources of the corresponding chiral aldehydes and ketones which are even more easily involved in such transformations. 3…”

Chiral methyl trans-2,2-dichloro-3-methylcyclopropanecarboxylate upon exposure to thiophenolate nucleophile

“…The reactions of gemdihalocyclopropanes with sulfur nucleophiles are known to give sufficiently stable dithiocyclopropanes. [16][17][18][19][20] Recently, numerous examples of stereoselective substitution in monobromocyclopropanes with heteroatomic nucleophiles have been described. 21,22 In continuation of our research, 10,11 the substitution of halogens by thiophenoxy groups in the chiral acids 1 has become the object of investigation.…”

“…20 This reaction proceeds quickly via an elimination-addition mechanism with formation of the proposed intermediate 3. 16,17 After a short boiling time, complete substitution of the halogens and formation of an equimolar mixture of diastereomeric esters 4 was detected by TLC and NMR.…”