I'm assuming that Samuel & Alexander are brothers and the sons of Alexander as per the Boston Transcripts.
*****
1771: The 1771 Mass. Tax Valuation List shows in Williamstown: Alexander Sloan with a house, 1 cow, no other information. [Samuel Sloan is also listed]
*****
1775: "Alexander Sloan of Williamstown" who appears in Mass. Soldiers and Sailors of the War of the Revolution, a sergeant in Capt. Samuel Sloan's Company of Minutemen, who marched in response to the alarm of 4/19/75. {This is the battle of Concord Bridge, where the minutemen fired the shot heard around the world}
******
A.B.L. says:"Sloan, Alexander (Conn). 2d Lieutenant of Elmore's Continental Regiment, 15th April, 1776; 1st Lieutenant 2d Canadian (Hazen's) Regiment, 16th December, 1776; resigned 2d June, 1777.
*****
There appears to be two or three different Alexander Sloan, all of Ct. one m. to a Margaret with 5 known children. Another Alexander m. to Hannah Cole b. abt 1720. and one b. 1742 that served in the Rev. War. No wife has ever been mentioned concerning the vet. Margaret is supposed to have d. in 1761, so Hannah Cole could not be a 2nd wife of Alexander.
******
Betsy Mae Sloane's DAR application names 14 children.
******
"A History of the County of Berkshire, Massachusetts In Two Parts" published in Pittsfield in 1829 (15-16 years after the death of Samuel Sloan), page 406, says, "Sam. Sloan, a native of Norwalk, came from Canaan, Con., and began between the village and Woodcock's corner about 1766, and his brother Alexander came soon, and afterwards built the house there, now occupied by Gershom Bulkley..."


Sources:
1. "DAR Patriot Index" National Society DAR 1966 [dpob, dpod/NY, Served as a Lt. from MA.]
2. Census 1790: Berkshire Co. MA. Pg. 39 Williamstown [Alex Sloan, 1-3-7]
3. 1771 Mass. Tax Valuation List
4. "American Biographical Library", (Salt Lake City, UT: Ancestry Incorporated, 1996.), Historical Register of Officers of the Continental Army During the War of the Revolution, 15th Virginia, pg. 500.
5. Boston Transcripts, (Queries from early 1900's, transcribed by Gloria Odom), [Alexander Sloan s/o Alexander & Margaret Sloan of Wilton CT.]

1. Almira S. Sloan b: 10 SEP 1767 in of Williamston, BERKSHIRE Co. MA.
2. Alexander Sloan b: 24 JUN 1769
3. William Sloan b: 12 OCT 1770
4. Cloe Sloan b: 7 SEP 1772
5. Ebenezer Sloan b: 2 JUN 1774
6. Phebe Sloan b: 22 SEP 1775
7. Beaman Sloan b: 22 DEC 1777 in NY. ?
8. Samuel Sloan b: 14 OCT 1779
9. Electa Sloan b: 6 JUN 1781
10. Lucinda Sloan b: 20 APR 1783
11. Permelia Sloan b: 12 MAY 1785
12. Hannah Sloan b: 15 MAR 1787
13. Ebenezer Sloan b: 25 DEC 1788
14. Tryphena Sloan b: 18 DEC 1791 in NY.

1. Title: Boston Transcripts
   Publication: Queries from early 1900's, transcribed by Gloria Odom
   Repository:
   Note: http://www.geocities.com/Heartland/Meadows/7937/bt11-5.htm
   Media: Book
   Text: [Alexander Sloan s/o Alexander & Margaret Sloan of Wilton CT.]
2. Title: DAR Patriot Index, Centennial Edition
   Publication: 1990
   Repository:
   Note: pg. 2689-90.
   Media: Book
   Text: [dpob, dpod/NY, Served as a Lt. from MA.]
3. Title: "A History of the County of Berkshire, Massachusetts in Two Parts"
   Author: Citizens of Berkshire County
   Publication: Samuel W. Bush, Pittsfield. 1829. 468 pages
   Repository:
   Note: Roberta Calhoun-Eagan's research, no copy on hand
   Media: Book
   Text: [Samuel Sloan, brother Alexander, relocation from Norwalk, Canaan Ct. to Berkshire Co. Ma.]
4. Title: Sloane, Bessie May
   Publication: DAR Application Nat. #155295
   Repository:
   Note: Roberta D. Calhoun-Eagan's source, no copy on hand.
   Media: Other
   Text: [dpod, 14 children]
5. Title: "American Biographical Library"
   Publication: Salt Lake City, UT: Ancestry Incorporated, 1996.
   Note: comprised of the following works:
   Biographical Directory of the American Congress, 1774-1949;
   Biographical Cyclopedia of American Women. 2 vols; Daughters of America (Women of the Century);
   Historical Register of Officers of the Continental Army During the War of the Revolution;
   Herringshaw's Encyclopedia of American Biography of the Nineteenth Century;
   American Biographical Notes: Being Short Notices of Deceased Persons, Chiefly Those Not Included in Allen's or Drake's Biographical Dictionary; Plymouth Colony;
   The Twentieth Century Biographical Dictionary of Notable Americans.
   Repository:
   Note: http://www.ancestry.com/search/rectype/inddbs/2016.htm
   Media: Other
   Page: Historical Register of Officers of the Continental Army During the War of the Revolution
   Text: 15th Virginia, pg. 500