25 with the reagent derived from 1,1-diiodoethane and diethylzinc (eq 12). 43,44 The level of induction was highly dependent on the nature of the nitrogen protecting group.An interesting cyclopropanation of an exocyclic olefin was reported by Ronald (eq 13). 45 The cyclopropanation of 2-methylenecyclohexanol using 13 Table 4. Cyclopropanation of (E)-3-Penten-2-ol 47 conditions ratio 31:32
A very effective chiral controller has been found for the conversion of allylic alcohols into the
corresponding enantiomerically enriched cyclopropanes using bis(iodomethyl)zinc. A variety of chiral,
nonracemic cyclopropylmethanols could be obtained according to this method. This methodology was extended
with success to the cyclopropanation of unconjugated and conjugated polyenes and homoallylic alcohols. The
cyclopropanation of allylic carbamates has also been investigated with this system, but it was found that
enantioenriched cyclopropylmethylamines are best prepared from enantioenriched cyclopropylmethanols.
In this report, we disclose our findings regarding the remarkable effect of a low-level impurity found in the solvent used for a ruthenium-catalyzed direct arylation reaction. This discovery allowed for the development of a robust and high-yield arylation protocol that was demonstrated on a multikilogram scale using carboxylate as the cocatalyst. Finally, a practical, scalable, and chromatography-free synthesis of the biaryl core of Anacetrapib is described.
Nickel-catalyzed, intramolecular and intermolecular reductive coupling of alkynes and epoxides affords synthetically useful homoallylic alcohols of defined alkene geometry. Very high regioselectivity is generally observed, and cyclizations proceed with complete selectivity for endo epoxide opening. This catalytic reaction represents the first use of a non-pi-based electrophile in a growing class of nickel-catalyzed, multicomponent coupling reactions, and is the first catalytic method of reductive coupling of alkynes and epoxides that is effective for both intermolecular and intramolecular cases, and mechanistically distinct from these, possibly involving a nickella(II)oxetane.
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