Synthesis of 2,2-dialkyl-1-aminocyclopropanecarboxylic acids from .alpha.-chloro ketimines

Synthesis and HPLC enantioseparation of the cyclopropane analogue of valine (c3Val)

“…3) was isolated. This result was not totally unexpected, as the formation of this g-butyrolactone as a consequence of cyclopropane cleavage had already been reported 24,27,29,30 in other routes to c 3 Val. It should be noted that in our previous work with cyclopropane a-amino acids bearing a variety of alkyl, aromatic, or functionalized substituents, we never observed any incompat- ibility between the cyclopropane system and the hydrolytic conditions mentioned above.…”

“…It should be noted that in our previous work with cyclopropane a-amino acids bearing a variety of alkyl, aromatic, or functionalized substituents, we never observed any incompat- ibility between the cyclopropane system and the hydrolytic conditions mentioned above. 38 -42 It seems that the instability of this and other 24,27,29,30 c 3 Val precursors to strong acid hydrolysis is related to their geminal disubstituted character and, therefore, to the possibility of formation of a tertiary carbocation through cyclopropane ring opening.…”

“…14,15 Thus, the reported routes 14 -30 to this cyclopropane amino acid most frequently involve the cyclization of different a-amino acid precursors bearing a leaving group at the g-position 16 -24 or the addition of sulfur 25 or phosphorus 26,27 ylides to a,b-dehydroamino acid derivatives. A Strecker-type approach 28 and the cyanide-induced ring closure of a-chloro imines 29,30 have also been applied to the preparation of c 3 Val. In some of these reports, the isolation of enantiomerically pure compounds has been addressed either by asymmetric synthesis 17,26 -28 or by chemical 25 or enzymatic 16 resolution procedures.…”

Catalytic Direct‐Type Addition Reactions of Alkylarenes with Imines and Alkenes

“…[16] In these systems,s trongly basic metal dialkylamides forms as product bases. Although the tertbutyl group is normally removed under very harsh acidic conditions, [18] no loss of the tert-butyl group was observed under various harsh acidic conditions in our initial trial. Thecombined use of LiTMP and KO t Bu was essential for efficient formation of the benzyl anion;n either LiTMP nor KO t Bu alone catalyzed the reaction (entries 2a nd 3).…”

One‐Pot Highly Stereoselective Synthesis of Cyano Aziridines via the CuCl‐Catalyzed Aminochlorination of α,β‐Unsaturated Nitriles and Intramolecular SN2 Substitution

“…In recent years, the most efficient methods for the synthesis of aziridines are via carbene and nitrene, but generally these approaches are mainly suitable for unfunctionalized alkenes (19–24). Although Darzens‐type reaction and other related processes can provide alternative methods for the preparation of functionalized aziridines (25–36), there is almost no report about the preparation of cyano aziridines until now (37,38). Thus, searching for the simple and efficient synthetic approaches for the preparation of cyano aziridines with readily available starting materials becomes a great challenge.…”