Synthesis of a-Nitro-a-diazocarbonyl Derivatives and Their Applications in the Cyclopropanation of Alkenes and in OH Insertion Reactions by Andre ¬ B. Charette*, Ryan P. Wurz, and Thierry Ollevier De ¬partement de Chimie, Universite ¬ de Montre ¬al, P.O. Box 6128, Station Downtown, Montre ¬al (Que ¬bec), Canada H3C 3J7 (tel:(514)343-2432;fax:(514)343-5900;e-mail:andre.charette@umontreal.ca;http://charette.corg.umontreal.ca) Dedicated to Professor Dieter Seebach on the occasion of his 65th birthday A facile and highly efficient method for the preparation of a-nitro-a-diazocarbonyl derivatives by a diazo- transfer reaction involving (trifluoromethyl)sulfonyl azide has been developed. These substrates undergo a rhodium-catalyzed cyclopropanation reaction with a variety of alkenes. A systematic study of the reaction indicated that the diastereoselectivity of the cyclopropanation could be effectively controlled through the modification of the steric bulk of the diazo reagent. A novel OH insertion reaction of the metal carbene complex derived from the a-nitro-a-diazocarbonyl reagent afforded the corresponding novel a-nitro-a-alkoxy carbonyl derivatives. Introduction. ± In recent years, diazo carbonyl chemistry [1] has been extensively exploited in several transformations such as in CH insertions, cyclopropanations 1 ), cascade reactions [3], XX(Br Br, I I)[4]andYH insertions (Y  O, N, S, P, Se, Si) 2 ), epoxidations [6], aziridinations [7], and in rearrangements or transfer reactions involving ylides 3 ). The largest body of literature encompasses the chemistry of a-diazo carbonyl, a-alkyl/aryl-a-diazocarbonyl, or a-vinyl-a-diazocarbonyl reagents, and it demonstrates exceptional versatility. Our research group has recently become interested in the preparation and synthetic applications of a-nitro-a-diazo carbonyls for the expedient synthesis of 2-substituted 1-aminocyclopropanecarboxylic acids (1) by reduction of the corresponding a-nitrocyclopropanecarboxylic acid 2 ( Scheme 1) 4 ). Additionally, the nitro compound could serve as a possible useful synthon towards the preparation of isoxazoline N-oxides 3 [10] 5 ),leadingto g-hydroxyamino acids 4 [11] or other g-substituted amino acids 5 ( Scheme 1)[12]. The simplest member of the class of constrained a-amino acids is the naturally occurring 1-aminocyclopropanecarboxylic acid (ACC, 6) 6 ). ACC, a natural plant growth hormone [14], was found to be a precursor for the biosynthesis of ethylene. Helvetica Chimica Acta ± Vol. 85 (2002) 4468 1 ) For a review, see [2]. 2 ) For a review, see [5a]; for examples of NH insertions, see [5b,c]. 3 ) For reviews, see [8]. 4 ) For R  H, see [9]. 5 ) See also [23]. 6 ) First isolation, see [13].