Steroidal Lariat Ethers: A New Class of Macrocycles and the Crystal Structure of N-(Cholesteryloxycarbonyl)aza-15-crown-5

Article abstract of DOI:10.1021/jo00390a001

Several examples of a new class of lariat ethers, those having steroidal side arms, are reported.These include the following carbon-pivot and nitrogen-pivot structures: 2-(3-dihydrocholesteryloxymethyl)-15-crown-5, mp 61-63 deg C; N-(3-cholesteryloxycarbonylmethyl)aza-15-crown-5, mp 85-86 deg C; N-(3-cholesteryloxycarbonylmethyl)aza-18-crown-6, mp 66-67 deg C; N-(3-dihydrocholesteryloxycarbonylmethyl)aza-15-crown-5, mp 60-61 deg C; N-(3-dihydrocholesteryloxycarbonylmethyl)aza-18-crown-6, mp 55-56 deg C; N-(3-cholesteryloxycarbonyl)aza-15-crown-5, mp 96-98 dec C; and N-(3-cholesteryloxycarbonyl)aza-18-crown-6, mp 82-84 deg C.Alkali-metal cation binding by these structures is generally weak, since the macroring binding is not augmented by side arm donor group participation.The high lipophilicity of the side arm does not enhance the caion binding strength.The X-ray crystal structure of one of these novel lariat ethers, N-(cholesteryloxycarbonyl)aza-15-crown-5 has been determined.This is the first example of an uncomplexed, 15-membered crown ether compound containing only nitrogen and oxygen heteroatoms.The macroring structure has one N-C-C-O torsion angle anti; thus one methylene group is turned inward