New synthetic reactions. X. Versatile cyclobutanone (spiroannelation) and .gamma.-butyrolactone (lactone annelation) synthesis

Abstract

. A solution of 2-trimethylsiloxybieyclo[5.3.03dec-l-ene (56 mg, 0.25 mmol) in 3 ml of 1,2-dimethoxyethane with a few milligrams of triphenylmethane as an indicator was treated with methyllithium at 25°until a color persisted. Then methyl iodide (0.3 ml) was added and the mixture stirred for 2 min. Water was added and the product extracted with 2 X 50 ml portions of hexane. An oil, 29 mg (71 %), was obtained upon evaporation of 1-methylbicyclo-[5.3.0]decan-2-one (48). The oil was a single spot by tic on silica gel: ir (CC14) 1736, 1412, 1374 cm"1; nmr (CC14) 1.13 (s) and 1.17 (s) total 3 H, cis and trans isomers; 1.2-2.3 (mult, 15 H); ms m/e (%) 166 (0.4), 151 ( 16), 110 (100), 95 (75), 81 (77), 68 (42), 67 (56), 55 (43), 41 (67). Anal. Caled for CuHlaO: 166.13576. Found: 166.13321. Acknowledgment. We thank the National Science Foundation and the National Institutes of Health for their generous support of our programs. We also thank the National Science Foundation and the Wisconsin Alumni Research Foundation for support in the purchase of nmr and mass spectrometric facilities.

Ti‐Catalyzed Barbier‐Type Allylations and Related Reactions

“…[42b] 15, [61] 22, [62] 23, [63] 24, [17] 25, [64] 27, [65] 37, [66] 38, [67] 39, [68] 41, [34] 47, [69] 48, [70] 49, [71] 51, [72] 65, [17] 66, [17] 73, [17] 77, [73] 81, [74] 89, [17] 90, [53] 92, [58] 95, [56] and 96.…”

Synthesis of unusually strained spiroheterocyclic ring systems and their exploits in synthesis

“…25 High selectivity for the desired diastereomer was achieved under the optimized conditions with lithium iodide in dichloromethane. Interestingly, the undesired diastereomer 29 was obtained with good diastereoselectivity by using lithium perchlorate in place of lithium iodide hinting at a change in mechanism to a carbocationic intermediate rather than halohydrin-type intermediates due to the multiple coordination sites available for the lithium atoms 24…”

“…An example is the rhodium-catalyzed synthesis of an eight-membered ring developed by Murakami (Scheme 14). 32 The o -styryl-cyclobutanone 50 was synthesized utilizing Trost’s cyclopropyl sulfoxonium ylide 24 procedure to generate oxaspiro[2.2]pentane 49 ,25 which was subsequently rearranged under protic conditions to yield the desired cyclobutanone 50 . Cyclobutenone 50 was transformed to octanone 51 via olefin insertion and subsequent hydrogenation.…”

Oxasecoalkylation via cyclobutanone intermediates

“…16,22 Vicinal glycols were created by nucleophilic opening of the epoxides at the primary carbon to avoid disturbing the asymmetric centers at C(5) and reduction of the lactones to the triols 43a and 43b. Baeyer-Villiger oxidation produced epoxy lactones 42a and 42b with retention of configuration at the center which migrated.…”

“…, 91 (1 I ) , 82(12), 81 (46), 80(14), 79 (45), 77(15), 69(9), 68(16), 67 (46), 66 ( I ] ) , 65(12), 56 (8), 55 (41), 54 (8), 53(33), 52(9), 51(14); mol wt calcd (C10H1203) 180.0786, found 180.0786.Cyclobutanone Syntheses. A.…”