A Novel Heterocycle-Stabilized Allylic Anion Route to Cyclopropanes, 1-Ethoxy-1-vinylethylene Oxides, 1-Hydroxyalkyl 2-Methoxyethyl Ketones, 1-Hydroxyalkyl Vinyl Ketones, .beta.-Ethoxy-.beta.-vinylalkyl Alcohols, .gamma.-Lactones, and .beta.,.gamma.-Unsaturated Carboxylic Acids