Hydrozirconation of C=X Functionalities with Schwartz's Reagent

Abstract

Hydrozirconation of various C=X functionalities with Schwartz's reagent is a powerful method for preparing functionalized organic molecules, for instance aldehydes, amines, and amides. The reactions of [Cp2Zr(H)Cl] with amides, lactams, nitriles or isocyanates proceed under mild conditions. These transformations are remarkably chemoselective as Schwartz's reagent is compatible with various functional groups, including electrophilic functionalities such as ester, nitrile, nitro, and halogens. This compatibility enables many hydrozirconation reactions to be combined with other synthetic methods, and enables performing the reactions in a one‐pot fashion as multicomponent processes.

Homologation chemistry with nucleophilic α-substituted organometallic reagents: chemocontrol, new concepts and (solved) challenges

“…In fact, this long-waiting transformation was previously limited by the full reduction of isocyanates to N-methyl amines. 63 Moreover, full chemocontrol emerged in the Matteson homologation of a boronic ester featuring a formamide unit, thus indicating how selecting the order of the transformation is critical for the target-oriented synthesis.…”

Recent Developments and Synthetic Applications of Nucleophilic Zirconocene Complexes from Schwartz's Reagent

“…Besides, this method allowed the use of other substrates (8 and 9), such as gaseous alkenes, and a lower loading of alkene and zirconium, with no loss in yields and enantioselectivities (Scheme 3) of the products (10). [24] In the same year, Fletcher and co-workers proved that the hydrozirconation asymmetric conjugate addition (HM-ACA) can be employed for the synthesis of a natural product (12). The desired compound isolated from the New Zealand liverwort Balantiopsis rosea and its enantiomer (13) were accessed in only one reaction step in moderate yields (53 % and 45 %, respectively), but excellent enantiomeric excess (95 % and 94 % ee, respectively).…”

“…Although previous reviews described important topics of the organozirconium chemistry, some important works were not covered, as well as recent contributions involving Schwartz's reagent . In this context, this review aims to cover C–C bond formation reactions employing Schwartz's reagent and the discussion will focus mainly on the recent developments (Scheme ).…”

“…reagent. [12][13][14][15][16][17][18] In this context, this review aims to cover C-C bond formation reactions employing Schwartz's reagent and the discussion will focus mainly on the recent developments (Scheme 1). Some aspects concerning the hydrozirconation followed by halogenation are also highlighted, since these products allow further functionalization, such as C-N, C-O and even C-C bonds formation, strategy that is widely employed in total synthesis.…”

Reductions of Imines Using Zirconocene Chloride Hydride

“…Zirconocene chloride hydride or chloridobis(η 5 ‐cyclopentadienyl)hydridozirconium ( 1 ), also known as a Schwartz reagent, was introduced in the 1970s by Wailes and Weigold It performs hydrozirconations of alkenes and alkynes, thus providing access to alkyl or alkenylzirconium compounds with diverse applications in organic and organometallic chemistry . Later, reducing capabilities of zirconocene chloride hydride towards polar groups were recognized . Schwartz reagent effectively reduces cyclic ketones, or semicyclic imides .…”