Chloroformates, addition with Grignard reagents

In an initial step, dibenzo[a,d] cyclohepten-5-one is reacted with the Grignard reagent of 3-di-methylaminopropyl chloride and hydrolyzed to give 5-(3-dimethylaminopropyl)-dibenzo[a,d] -[1,4] cycloheptatriene-5-ol. Then 13 g of that material, 40 ml of hydrochloric acid, and 135 ml of glacial acetic acid is refluxed for 314 hours. The solution is then evaporated to dryness in vacuo and added to ice water which is then rendered basic by addition of ammonium hydroxide solution. Extraction of the basic solution with chloroform and removal of the solvent from the dried chloroform extracts yields the crude product which when distilled in vacuo yields essentially pure 5-(3-dimethylaminopropylidene)-dibenzo[a/f ] [ 1,4] cycloheptatriene, BP 173°C to 177°C at 1.0 mm. 

Addition of vinyl, but-2-enyl, and pent-4-enyl Grignard reagents to 3,3-dimethylcyclopropene, followed by quenching with solid carbon dioxide or ethyl chloroformate, gave 2-substituted 3,3-dimethylcyclopropanecarboxylates and -carboxylic acids 7 in poor to moderate yield... 

Aminopyridine-3-ketimines, prepared by addition of Grignard or lithium reagents to nicoti-nonitriles, have been cyclized with phosgene, ethyl chloroformate, or carbonyl diimidazole to give pyrido[2,3-f/lpyrimidin-2( 1 f/)-ones, e.g. 47.73 75... 

The linear notation can have the same form as before with the specification that the ambivalent atom X is placed first in the clockwise atom list. In this way no indicator for the unshared pair is necessary and the atom list will have an odd number of items, hence distinguishing it from homovalent reactions. A simple example is the three-cycle formation of a Grignard reagent such as 0[MgCBr]. The five-cycle cases in Schemes 3 and 4 would then be ls[MXCCX] and 3vs [SCCCC]. A common ambivalent atom is carbene the designation for dichlorocarbene formed from chloroform is shown in Scheme 14 and its addition to an alkene in Scheme IS. 

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