Grignard reagents, reaction with carbamates

Similar reactions of carbamates 22 with Grignard reagents in diethyl ether or tetrahydrofuran lead, without isolation of the imine and/or ketone intermediate, to 4-substituted quinazolin-2(l//)-ones 23, albeit in only 11% yield. 

Transformation of 1,3-diamino-2-propanol (144) into vicinal diamines has been reported. Thus, the bis(benzyloxycarbonyl) derivative of (144) was mesylated to give (145), which was converted into 1-benzyloxycarbonylaziridine (146). Acetic acid and HCl reacted at the ring carbon of (146) affording 2,3-diamino-1-propanol (147) and l-chloro-2,3-diaminopropane (148 Scheme 68). On the other hand, the reaction of (146) with Grignard reagents and sodio malonates resulted in the loss of the carbamate protecting group. In contrast, the sulfonamide derivative (149) could be converted into diamines (151) and (152) via 1-tosylaziridine (150 Scheme 68). 

In the area of organometallic chemistry, we begin with a procedure for the palladium-catalyzed animation of aryl halides and aryl triflates, illustrated by syntheses of N-HEXYL-2-METHYL-4-METHOXYANIUNE and N-METHYL-N-<4-CHLOROPHENYL)-ANILINE. The next procedure describes the synthesis of 1,2,3,4-TETRAHYDROCARBAZOLE by the palladium-catalyzed annulation of ketones with o-iodoaniline. Next, a procedure for the synthesis of 2,7-DIMETHYLNAPHTHALENE via the nickel-catalyzed coupling of aryl O-carbamates with Grignard reagents is presented. The fourth procedure in this section describes the synthesis of 5-METHYL-2,2 -BIPYRIDINE by a Negishi cross-coupling reaction... 

The Knoevenagel condensation is the method of choice for the preparation of a,p-unsaturated dicarbonyl compounds and related compounds and only a few alternative methods have been developed. However, with the traditional Knoevenagel condensation there are problems with the reactivity of ketones, with the competitive Michael addition occuring in the reaction of some active methylene compounds. There is also a problem with steieocontrol in the synthesis of Knoevenagel products from unsymmetrical 1,3-dicarbonyl compounds. An alternative method is the addition of Grignard reagents to vinylogous carbamates (see Section 11.2.6). Another possibility is the reaction of a metal ketimate with malonodini-trile to yield ylidenemalonodinitriles (see Section 11.3.1.7). ... 

Although discovered and assessed in scope and limitation over a decade ago [68, 74], the aryl O-carbamate cross-coupling partner for the Kumada-Corriu reaction has not seen widespread application. This conceptual 1,2-dipole synthetic equivalent (Scheme 14.10) has been reasonably well tested using simple, not necessarily always aromatic, Grignard reagents and these have been compared with the... 

Reaction with Alkyl Halides. The Grignard reagent (1) can be alkylated by allyl halides to afford the homoallylsilane. The use of a nickel(II) catalyst facilitates coupling of the Grignard reagent (1) to vinyl halides and aryl halides, triflates and O-carbamates and provides a useful method for the preparation of allyl- andbenzylsilanes (eq 7). Palladium catalysis is also effective to couple (1) with vinyl halides. 

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